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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
8 th International Conference on Radiation Effects on
Semiconductor Materials, Detectors and Devices
October 12-15, 2010
Dipartimento di Fisica ed Astronomia
Largo E. Fermi 2, Firenze Italy
ABSTRACT BOOK
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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
Conference Program
Tuesday October 12
2
8 th International Conference on
Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
Dipartimento di Fisica ed Astronomia
Largo E. Fermi 2, Firenze Italy
Short Course on Semiconductor Detectors for Medical Applications
08:30 – 09:15 Registration
09:00 – 09:15 Welcome
Prof. Pier Andrea Mandò , Director of
Istituto Nazionale di Fisica Nucleare
(INFN) Sezione di Firenze, Italy
09:15 – 10:05
Accelerators and Detectors in Medical Physics Prof. Roberto Cirio, University of Torino,
and INFN, Italy
10:05 – 10:55
Silicon detectors: basic principles of operation Prof. Hartmut F. W. Sadrozinski, UCSC
Santa Cruz, CA, USA
10:55 – 11:15 Coffee break
11:15 – 12:15
Diamond detectors and dosimeters for medical
applications
Prof. Claudio Manfredotti, University of
Turin and INFN, Italy
12:15 – 12:55
Semiconductor detectors for X ray radiology:
current and future trends
Prof. Renata Longo, University of Trieste
and INFN, Italy
12:55 – 14:30 Lunch
Current and Future Applications of Single Prof. Hartmut F. W. Sadrozinski, UCSC
14:30 – 15:20 Particle Tracking in Medical Imaging and
Radiobiology
Santa Cruz, CA, USA
15:20 - 16:10
Thermoluminescence and Optically Stimulated
Luminescence in radiotherapy dosimetry
Prof. Pawel Olko, Institute of Nuclear
Physics, Krakow, Poland
16:10 – 16.30 Coffee break
16:30 – 17:20
Silicon-based
Radiotherapy
Dosimeters for Clinical Dr. David Menichelli, IBA Dosimetry
Group GmbH, Germany
17:20 – 18:10
Silicon Photomultipliers: working principles
and applications to PET
Dr. Maria G. Bisogni, INFN an University
of Pisa, Italy
Directors of the School: Prof. Marta
18:10 Summary
Bucciolini, Univ. Florence and INFN, Italy;
Dr. Carlo Civinini, INFN Firenze, Italy
Wednesday October 13
8 th Int. Conference on Semiconductor Materials, Detectors and Devices
08:30 – 09:15 Registration
09:15 – 09:30 Conference Welcome
09:30 – 10:15
Opening Invited Overview Talk
Ionizing Radiation in Space Piero Spillantini INFN and University of
Florence, Italy
Session 1: Silicon Detectors at LHC
Invited Talk
Maria Assunta Borgia University of
10:15 – 10:45 Operation and performance of CMS silicon California, Davis, Physics Dept., USA
tracking detector
on behalf of the CMS Collaboration
10:45 – 11:15 Invited Talk Ingo Torchiani, CERN Switzerland, on

8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
ATLAS Silicon Microstrip Tracker Operation
and Performance
11:15 – 11:45 Coffee break
Invited Talk
11:45 – 12:15 First Results from the LHCb Vertex Locator
12:15 – 12:35
Evolution of Silicon Sensors Characteristics of
the Current CMS Tracker
12:35 – 14:00 Lunch
Session 2 New Detector Structures
Invited Talk
Monolithic pixel detectors in Silicon On
14:00 – 14:30
Insulator technologies: design review and first
results
Simulation of new p-type strip detectors with
14:30 - 14:50 trench to enhance the charge multiplication
effect in the n-type electrodes
Annealing studies on X-ray and neutron
14:50 – 15:10 irradiated CMOS Monolithic Active Pixel
Sensors
Heavy Ion-induced SEE measurements on a 130
15:10 – 15:30 nm CMOS test chip for LHC applications and
beyond
Continuous measurement of radiation damage
15.30 - 15:50
of standard CMOS imagers
15:50 – 16:20 Coffee break
Session 3 Pixel sensor Upgrades
Invited Talk
Limitation on upgrade ID Layout from Particle
16:20 – 16:50
Fluxes, Signal-to-Noise, and Occupancy
16:50 – 17:10
The upgrade of the CMS pixel detector
17:10 – 17:30 Radiation hardness studies of n+ -in-n planar
pixel sensors for the ATLAS upgrades
17:30 – 17:50
Characterization and performance of Silicon nin-p
Pixel Detectors for the ATLAS Upgrades
New 3D-Trench Electrode Si Detectors for
17:50 – 18:10 Radiation Hard Detectors for SLHC and for Xray
applications
18:10 – 18:30
High efficiency readout circuits for large
matrices of pixels
Thursday October 14
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behalf of the ATLAS SCT Collaboration
Tomasz Szumlak, Krakow University of
Science and Technology, on behalf of the
LHCb Vertex Locator Group
Christian, Barth , Karlsruhe Institute of
Technology (KIT) and IEKP, Germany on
behalf of the CMS Tracker Collaboration
Serena Mattiazzo University of Padova
Department of Physics, Italy & INFN
Sezione di Padova
Pablo Fernandez-Martinez Centro Nacional
de Microelectronica, IMB-CNM-CSIC,
Spain
Dennis Doering Institut für Kernphysik,
Goethe University Frankfurt/M, Germany
Alessandro Gabrielli INFN, Istituto
Nazionale di Fisica Nucleare, Italy
Leonello Servoli, INFN Perugia, Italy
Hartmut F.-W. Sadrozinski
SCIPP, UCSC, CA, USA
on behalf of ATLAS ID Upgrade
Carlotta, Favaro Universitaet Zuerich,
Physik Institut, Switzerland on behalf of
the CMS Collaboration
Andre Rummler TU Dortmund, Lehrstuhl
fuer Experimentelle Physik IV, Germany
Philipp Weigell, MPI für Physik, Germany
Zheng Li, Brookhaven National
Laboratories, Upton, NY, USA
Filippo Giorgi, INFN, Istituto Nazionale di
Fisica Nucleare, Italy
Session 4
Development of Ultra Rad. Hard Si detectors
Invited Talk
Vladimir Eremin Ioffe Physical-Technical
09:00 - 09:30
Avalanche effect in Si heavily irradiated
detectors: physical model and perspectives for
application
Institute RAS, SSE, Russia
Invited Talk
Elena, Verbitskaya Ioffe Physical-
09:30 – 10:00
Development of radiation hard edgeless
detectors with current termination structure on
p-type silicon
Technical Institute RAS, SSE, Russia
10:00 – 10:20 Development of planar detectors with active Marco Povoli University of Trento, &

10:20 – 10:40
10:40 – 11:00
8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
edge
Performance Characteristics of p + n MCz Si Pad
Sensors after Mixed Irradiation: Impact on
Space Charges, Electric Field Distribution
using Simulation Approach
Surface Properties of Si Sensors pre-rad and
post-rad
11:00 – 11:20 Coffee Break
Session 5: Radiation Damage in Silicon
Invited Talk
11:20 - 11:50 Radiation damage effects in silicon induced by
electrons of different energy
11:50 – 12:10
New results on the annealing behaviour of the
E4/E5-defect
Edge-TCT measurements with irradiated
12:10 - 12:30 microstrip detectors
12:30 – 12:50
Fluence dependent variations of barrier and
generation currents in neutron and proton
irradiated Si pin diodes
12:50 – 13:10
Test beam results of Current Injected Detectors
(CID) irradiated up to 5×10 15 1 MeV neq/cm 2 )
13:10 – 13:30
Characterization of low resitivity
Magnetic Czochralski detectors
p-on-n
13:30 – 14:30 Lunch
14:30 – 16:00 Poster Session
17:00-19:00 Visit to Museo Bardini and Conference Cocktail
20:00 – 23:00 Social Dinner DownTown Florence at “ Beppa Fioraia
09:00 – 09:30
09:30 – 09:50
09:50 – 10:10
10:10 – 10:30
Friday, October 15
Session 6: Tracker Detectors Upgrades
Invited:
Campaign to Indentify the Baseline Sensor
Technology for the Phase II Tracker Upgrade
Silicon Detectors for the sLHC
Update of the annealing scenario for irradiated
silicon p-in-n microstrip sensors
The ATLAS Tracker Upgrade: Radiation Hard
Silicon Strip Detectors for the sLHC
Beam Test Measurements with Planar n-on-p
10:30 – 10:50 Silicon Microstrip Sensors Irradiated to sLHC
fluences
10:50 – 11:20 Coffee break
11:20 – 11:50
11:50 – 12:10
12:10 – 12:30
Session 7: Diamond Detectors and Devices
Invited Talk:
Diamond for high energy radiation and particle
detection
Diamond growth structural defect removal
strategy for radiation detectors fabrication
Laser processing of Silicon-On-Diamond:
experimental results and perspectives
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INFN Padova, Gruppo collegato di Trento,
Italy
Ajay Kumar Srivastava
Institute for Experimental Physics,
University of Hamburg, Germany
Hartmut F.-W. Sadrozinski SCIPP, UC
Santa Cruz USA on behalf of the ATLAS
ID Upgrade
Eckhart Fretwurst
University of Hamburg, Germany
Alexandra Junkes
Hamburg University, Germany
Gregor, Kramberger Jožef Stefan Institute,
Department of Experimental Particle
Physics, Slovenia
Tomas Čeponis
Vilnius University, Institute of Applied
Research, Lithuania
Jaakko Härkönen
Helsinki Institute of Physics, Finland
Nicola Pacifico CERN, PH/DT, CH
Karl-Heinz Hoffmann, Karlsruher Institut
für Technologie, Germany on behalf of the
CMS Tracker Collaboration
Ulrich Parzefall University of Freiburg,
Institute of Physics, Germany on behalf of
the RD50 Collaboration
Craig Wigglesworth University of
Liverpool Physics UK
Ian Dawson University of Sheffield on
behalf of the ATLAS SCT Collaboration
Liv Wiik University of Freiburg, Germany
on behalf of the ATLAS Upgrade Silicon Strip
Detector Collaboration
Harris Kagan Ohio State University USA,
on behalf of the RD42 Collaboration
Volpe Pierre-Nicolas, Commissariat à
l'Energie Atomique, France
Silvio Sciortino INFN Florence, Italy

8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
12:30 – 12:50
Laser processing
theoretical insights
of Silicon-On-Diamond: Stefano Lagomarsino, INFN Florence, Italy
12:50 – 13:10
Charge Collection Efficiency Mapping of a
CVD diamond Schottky Diode
Claudio Manfredotti University of Torino
and INFN, Italy
13:10 – 14:30 Lunch
Session 8: Medical Applications
14:30 – 15:00
Invited Talk
PRIMA: an apparatus for medical application
Valeria Sipala, INFN Catania, on behalf of
the PRIMA INFN Project
15:00 – 15:20
Single crystal CVD diamond for conventional
and novel therapy techniques
Nicolas Tranchant, Commissariat à
l'Energie Atomique – CEA LIST France
Simulation and characterization of different Michele Benetti, Universita' di Trento –
15:20 – 15:40 setups for gamma ray detection using SiPMs INFN, DISI - INFN gruppo collegato di
and LYSO scintillators
Trento sezione di Padova, Italy
Dosimetric Characterization of Synthetic Single Gianluca Verona Rinati Università di
15:40 – 16:00 Crystal Diamonds for Radiotherapy
Roma “Tor Vergata”, Dipartimento di
Application
Ingegneria Meccanica, Italy
16:00 – 16:30 Coffee break
Session 9: Wide gap semiconductors and
devices
16:30 – 16:50
AC—coupled pitch adapters for silicon strip
detectors
Jaakko Härkönen
Helsinki Institute of Physics, Finland
UV photoconductivity and Thermally Riccardo Mori Dipartimento di Energetica,
16:50 – 17:10 Stimulated Currents in nanostructured TiO2
for dye-sensitized solar cells
Università di Firenze and INFN Firenze
17:10 – 17:30
Contacts to high resistivity semiconductors Arie Ruzin, Tel Aviv University, Faculty
of Engineering
Study of the luminescence features of single- Silvia Calusi, University of Firenze, Dept.
17:30 – 17:50 crystal CVD diamonds by means of the Ion of Physics and Astronomy, Italy, INFN-
Beam Induced Luminescence (IBIL) technique Firenze, Italy
17:50 – 18:00 Conference Farewell
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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
Wednesday, October 13
Opening Overview talk
Ionizing Radiation in Space
Piero Spillantini
INFN and University of Firenze, Italy
The composition, distribution and time evolution of the harsh radiation environment in the space
around the Earth is described. The solar wind filling the radiation belts, the origin and distribution
of the major solar energetic events and their effects, as well as the continuous flux of the galactic
cosmic rays penetrating from outside the heliosphere are considered. These phenomena severely
limit the orbit of spacecrafts and the performance of the onboard experiments, increasing their
complexity and cost. Some examples of most recent cosmic rays experiments in space and of their
instrumentation will be described and discussed.
Session 1: Silicon Detectors at LHC
Operation and performance of CMS silicon tracking detector
Maria Assunta Borgia
University of California, Davis, Physics Dept., USA
On behalf of the CMS Collaboration
The experiments now operating at the CERN Large Hadron Collider all include large, state of the
art silicon detector systems for measuring the trajectories of charged particles from the protonproton
collisions. The CMS silicon tracking detector is the largest silicon tracking detector every
built, with almost 10 million microstrip sensor elements and 66 million pixels. It has been operating
very successfully since collisions began in late 2009 and the performance is very consistent with the
design goals. Results from the early operation will be shown and comments made on the challenges
of designing and constructing such systems.
ATLAS Silicon Microstrip Tracker Operation and Performance
Ingo Torchiani
CERN, Switzerland
on behalf of the ATLAS SCT Collaboration
In December 2009 the ATLAS experiment at the CERN Large Hadron Collider (LHC) recorded the
first proton-proton collisions at a centre-of-mass energy of 900 GeV. The SemiConductor Tracker
(SCT) is the key precision tracking device in ATLAS, made up from silicon micro-strip detectors
processed in the planar p-in-n technology. The completed SCT has been installed inside the ATLAS
experimental hall. After the commissioning phase it arrived to the first LHC pp collision runs in
very good shape: 99.3% of the SCT strips are operational, noise occupancy and hit efficiency
exceed the design specifications, the alignment is already close enough to the ideal one to allow on-
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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
line track reconstruction and invariant mass determination. In the talk the current status of the SCT
will be reviewed, including in particular results from the latest data-taking periods of the 2010
running at centre-of-mass energies of 7 TeV, and from the detector alignment. We will report on the
operation of the detector and observed problems. The main emphasis will be given to the
performance of the SCT with the LHC in high-energy collision mode in a comparison with the
expected parameters and with the Monte Carlo simulations.
First Results from the LHCb Vertex Locator
Tomasz Szumlak
Krakow University of Science and Technology
on behalf of the LHCb Vertex Locator Group
LHCb is a dedicated experiment to study new physics in the decays of beauty and charm hadrons at
the Large Hadron Collider (LHC) at CERN. The beauty and charm hadrons are identified through
their flight distance in the Vertex Locator (VELO), and hence the detector is critical for both the
trigger and offline physics analyses. The VELO is the silicon detector surrounding the interaction
point, and is the closest LHC vertex detector to the interaction point, hence receiving the highest
radiation dose. It is located only 7 mm from the LHC beam during normal operation. The detector
operates in an extreme and highly non-uniform radiation environment. The VELO consists of two
retractable detector halves with 21 silicon micro-strip tracking modules each. A module is
composed of two n+-on-n 300 micron thick half disc sensors with R-measuring and Phi-measuring
micro-strip geometry, mounted on a carbon fibre support paddle. The minimum pitch is
approximately 40 µm. The current detector is also equipped with one n-on-p module, the first at the
LHC. The detectors are operated in vacuum and a bi-phase C02 cooling system used. The detectors
are readout with an analogue front-end chip and the signals processed by a set of algorithms in
FPGA processing boards. The performance of the algorithms is tuned for each individual strip using
a bit-perfect emulation of the FPGA code run in the full software framework of the experiment.
Radiation monitoring procedures have been put in place for future monitoring as the dose increases.
This is based on regular IV and noise versus voltage data outside physics fills. In addition data is
periodically taken during LHCb physics fills with detectors at different voltages from which the
CCE can be determined. The VELO has been commissioned and successfully operated during the
initial running period of the LHC. The detector has been time aligned to the LHC beam to within 2
ns, and spatially aligned to 4 µm. The halves are inserted for each fill of the LHC once stable beams
are obtained. The detector is centred around the LHC beam during the insertion through the online
reconstruction on the primary vertex position. Preliminary operational results show a signal to noise
ratio of 20:1 and a cluster finding efficiency of 99.6 %. The small pitch and analogue readout, result
in a best single hit precision of 4 µm having been achieved at the optimal track angle.
Evolution of Silicon Sensors Characteristics of the Current CMS Tracker
Christian, Barth
Karlsruhe Institute of Technology (KIT), Institut für experimentelle Kernphysik (IEKP), Germany
on behalf of the CMS Collaboration
The CMS silicon strip tracker is the largest detector of its kind. It is expected to operate at the LHC
for more than 10 years. In order to quantify aging effects, it is important to keep track of the
evolution of fundamental detector properties under radiation and thermal fluctuations. Our aim is to
define monitoring procedures to determine the characteristics regularly. In this talk we focus on the
silicon sensor's full depletion voltage. We present the first results obtained with two different
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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
methods: a standard one with signal from particles and a newly developed approach based on noise.
In addition we compare our output with the measurements performed during the construction.
Session 2: New Detector Structures
Monolithic pixel detectors in Silicon On Insulator technologies: design review and first results
Serena Mattiazzo* 1,2 , Marco Battaglia 3,4 , Dario Bisello 1,2 , Devis Contarato 3 , Peter Denes 3 , Piero
Giubilato 1,2 , Devis Pantano 1,2 , Luca Silvestrin 1,2 , Mario Tessaro 1,2
1 University of Padova Department of Physics, Italy
2 INFN Sezione di Padova, Italy
3 Lawrence Berkeley National Laboratory, USA
4 University of California, Santa Cruz, SCIPP, USA
Silicon on insulator (SOI) technology allows the integration of CMOS electronics on a thin silicon
layer which is electrically insulated from the wafer substrate by means of a thin buried-oxide layer
(BOX). Monolithic pixel sensors for charged particle detection and imaging applications can be
built in SOI technology by contacting a high-resistivity handle wafer substrate through the BOX. A
full CMOS circuitry can be integrated on top of each pixel, and the sensor substrate reverse biased
and depleted to improve charge collection. A commercial deep-submicron SOI CMOS process by
OKI, coupled with high-resistivity silicon substrates, was recently made available through KEK.
The CMOS electronics is implanted on a 40nm thin silicon layer, on top of a 200nm thick BOX
contacting a 700 Ωcm silicon substrate, thinned to 250um and plated with a 200nm thin Al layer
that allows back-biasing. The talk will review the design and characterization of the chips designed
at LBNL in collaboration with INFN and University of Padova. Studies on the effect of different
substrate bias conditions on the Total Dose tolerance of the technology and Single Event Upset
micromapping analysis will be given. In addition, results of the first test beam with 200GeV
hadrons on the most recent SOI chip will be presented.
Simulation of new p-type strip detectors with trench to enhance the charge multiplication
effect in the n-type electrodes
Pablo Fernandez-Martinez 1 , Giulio Pellegrini 1 , Manuel Lozano 1 , Celeste Fleta 1 , David Quirion 1 ,
Miguel Ullan 1 , Salvador Hidalgo 1 , David Flores 1 , Gianluigi Casse 2
1 Centro Nacional de Microelectronica, IMB-CNM-CSIC, Spain
2 University of Liverpool Department of Physics and Astronomy, UK
This paper shows the simulation results of new p-type strip detectors with trench electrodes to
enhance the charge multiplication effect in the irradiated device. The new design includes baby
microstrip detectors (area = 1 cm 2 ) with a strip pitch of 80 µm and p-stop isolation structures. The
strip have a 5 µm - wide trench along all its length, filled and doped with polysilicon to create a
deep n+ contact into the material bulk. The depth of the trench can be varied in order to study the
influence of the electric field in the charge multiplication effect in heavily irradiated samples. Some
alternative designs have also been studied to establish a comparison between the different
technological proposals. Simulations reproduce the electrical behaviour under different irradiation
conditions, taking into account the damage accumulated after irradiation with neutrons and protons
with several fluence values. Charge collection process is simulated for the case of a minimum
ionizing particle incidence. This has the twofold scope of offering a new tool for understanding the
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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
multiplication mechanism and providing a method for possibly boosting the charge collection of
planar devices. The understanding of the charge multiplication effect in irradiated microstrip
devices is investigated by bringing the electric field at different depths in the bulk of planar sensors.
Besides, if a significant improvement of the collected charge will be found, this geometry can be
directly applied to microstrip sensors. The investigation of these effects using the depth of the strip
trench as a parameter provides important indications on the ability of this modified electrode
geometry to control and optimize the charge multiplication effect in order to fully recover the
collection efficiency of heavily irradiated microstrip detectors at reasonable bias voltage compatible
with the limitation of the CERN LHC experiment. The work has been done in the framework of the
RD50 CERN collaboration.
Annealing studies on X-ray and neutron irradiated CMOS Monolithic Active Pixel Sensors
Michael Deveaux 1 , Dennis Doering* 1 , Christian Müntz 1 , Joachim Stroth 1 , Christian Trageser 1 ,
Franz M. Wagner 2
1 Institut für Kernphysik, Goethe University Frankfurt/M, Germany
2 Forschungsneutronenquelle Heinz-Maier-Leibnitz (FRM II), TU Munich, Germany
CMOS Monolithic Active Pixel Sensors (MAPS) demonstrated excellent performances in tracking
detectors for charged particles. They provide an outstanding spatial resolution (few µm) and
detection efficiency (>99.9%) in combination with very low material budget (0.05% X0 per sensor)
and good radiation tolerance (> 1MRad, > 3x10 13 neq/cm 2 ) [1]. MAPS are the technology of choice
for micro vertex detectors for the heavy ion experiments STAR and CBM and a potential candidate
for a micro vertex detector at the ILC. Due to the luminosities needed to address the physic
questions, radiation tolerance is in the focus of the sensor optimization. To approach the
requirements of these experiments regarding radiation tolerance, the radiation tolerance of the
sensors is being evaluated and improved within a joined R&D project carried out by the IPHC
Strasbourg and IKF Frankfurt. This contribution focuses on the radiation damage in the sensors
which could be reduced by thermal annealing. This was suggested by previous studies [2] which
were however restricted to ionizing radiation damage only. We reproduced the results and
complemented the measurements by a first systematic study of the annealing effects of neutron
irradiated MAPS. We will demonstrate the feasibility of annealing ionizing radiation damage in the
presence of non-ionizing radiation damage. The results of the studies will be presented and the
option to recover a strongly irradiated, MAPS based vertex detector by means of thermal treatment
will be discussed.
[1] M.Deveaux. Design considerations for the Micro Vertex Detector of the Compressed Baryonic
Matter experiment. ArXiv e-prints, June 2009.
[2] G.Deptuch. A new Generation of Monolithic Active Pixel Sensors for Charged Particle
Detection. IPHC Strasbourg, 2002.
Heavy Ion-induced SEE measurements on a 130 nm CMOS test chip for LHC applications
and beyond
Andrea Candelori 1 , Giuseppe De Robertis 2 , Alessandro Gabrielli* 3 , Serena Mattiazzo 1 , Devis
Pantano 1 , Antonio Ranieri 2 , Mario Tessaro 1
1 INFN – Padova Italy
2 INFN – Bari Italy
3 INFN – Bologna and Department of Physics, University of Bologna Italy
On behalf of the DACEL2 Collaboration
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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
Within the perspective to develop a radiation-tolerant circuit, a digital test microelectronic device
has been designed and fabricated by using a standard-cell library of a 130-nm CMOS technology,
including three different and standard architectures to correct circuit malfunctions induced by the
occurrence of Single-Event Effects (SEE's). SEE's are one of the main reasons of failures affecting
electronic circuits operating in harsh radiation environments, such as in experiments performed at
High Energy Physics (HEP) colliders at the Large Hadron Collider in Geneva. This paper presents
the results of SEE cross section measurements performed on a test digital device exposed to high
energy heavy ion beams at the SIRAD irradiation facility of the INFN National Laboratories of
Legnaro (Padova Italy). In particular, the article analyzes the behavior of a test digital device, i.e. a
long Flip-Flop shift-register chain (256 bits), with respect to the issue of SEE occurrences. In
addition the paper describes how to improve the radiation hardness by introducing some special
architectures, mostly used to correct digital circuit errors caused by SEE. In particular we have
compared the results obtained from the unprotected circuit with the ones obtained using a Hamming
code and a Triple Time redundancy (TTR). In the Hamming coding technique a full protection on
single bit errors has been introduced in each register. This solution is capable to correct corrupted
data only in case of one bit fault in the complex data transmitted chain. Conversely, in a TTR
architecture that adopts only once the combinatorial part of the circuit without any replica, the
circuit uses a three time replica of the system clock, delayed three times by a fixed quantity, for
strobing the input data into the sequential part of the logic. Its output is finally voted before sending
the results into the input of the combinatorial logic of the circuit. The results seem to confirm the
validity of the TTR architecture as a possible remedy against SEE occurrences in the considered
commercial CMOS 130 nm technology for High Energy Physics and radiation hardness
applications, such as in the LHC apparatus, even if it must be taken into account a circuit area
increase by a factor 2.4 and a power consumption increase by a factor 2.6 with respect to the
unprotected circuit.
Continuous measurement of radiation damage of standard CMOS imagers.
Leonello Servoli *1 , Fabrizio Bizzarri 1,2 , Daniele Passeri 1,2 , Pisana Placidi 1,2
1 INFN Perugia, Italy
2 Univ. Studi Perugia, Dip. Ingegneria Elettronica, Italy
In this work we have irradiated a standard CMOS imager with a 24 MeV proton beam at LNS up to
a nominal fluence of 1E14 protons/cm 2 . The device under test was a standard VGA Micron
Technology detector (now Aptina Imaging) featuring 5.6x5.6 micrometers pixel size, 130 nm
technology. For the test purposes, the device was masked with an aluminum collimator (1mm hole
diameter) to protect the electronic on the periphery of the chip. The irradiation has been performed
in time steps of approximately the same period, changing the beam intensity from step to step. The
overall irradiation lasted 10 hours. During the damaging the detector was fully operational and we
have been able to monitor the progressive damaging of the sensor and the associated on-pixel
electronics in terms of detection efficiency, charge collection and noise. We found that the detector
is still working at 10 13 protons/cm 2 , with a moderate increase of the noise (20%), while after that
value the behaviour of the on-pixel electronics (which was not designed to be radiation tolerant up
to such a fluence) resulted in a malfunctioning of the irradiated pixels.
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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
Session 3: Pixel Sensor Upgrades
Limitation on upgrade ID Layout from Particle Fluxes, Signal-to-Noise, and Occupancy
Hartmut F.-W. Sadrozinski
University of California Santa Cruz, CA, USA
on behalf of ATLAS ID Upgrade
The high luminosities planned for the sLHC present challenges for semiconductor detector design
on two fronts. First, the high integrated luminosity implies a large total number of particles through
the detector, and this fluence generates radiation damage in the semiconductor bulk. Second, the
high instantaneous luminosity gives rise to high channel occupancy, even in finely segmented
detectors. This increased occupancy is a challenge for readout architecture design and for the
tracking algorithm development. Understanding the limitations imposed by the two challenges is
aiding in the optimization of the layout of the Upgrade ATLAS Inner Detector. This talk collects
the currently available data that could give information on the limitations on the upgrade ID layout
from the estimated particle fluxes, signal-to-noise ratio, and occupancy, and compares it with the
present ATLAS Upgrade ID layout.
The upgrade of the CMS pixel detector
Carlotta, Favaro
Universitaet Zuerich, Physik Institut, Switzerland
on behalf of the CMS Collaboration
The CMS inner pixel detector will be replaced for the LHC luminosity upgrade. The plan foresees
an ultra low-mass system with four barrel layers and three endcap disks on either end. With the
expected increase in particle rates, the frontend electronics will include digitized readout and larger
bandwidth. An overview of the envisaged design options for the upgraded CMS pixel detector is
given, as well as estimates for the tracking and vertexing performance.
Radiation hardness studies of n + -in-n planar pixel sensors for the ATLAS upgrades
Claus Goessling, Reiner Klingenberg, Daniel Muenstermann, Andre Rummler*, Georg Troska
TU Dortmund, Lehrstuhl fuer Experimentelle Physik IV, Germany
ATLAS plans two major upgrades of its pixel detector on the path to SLHC: First, the insertion of a
4th pixel layer (Insertable B-Layer, IBL) with a mean sensor radius of only $33\, \textrm{mm}$ is
envisaged for 2014. This would enable the ATLAS tracker to cope with an increase of LHC's peak
luminosity to about 3 10 34 cm -2 s -1 which requires a radiation hardness of the sensors of up to
5x10 15 neqcm -2 . Towards the end of this decade, a full replacement of the inner tracker is foreseen to
cope with luminosities of up to 10 35 cm -2 s -1 at SLHC. Here, the innermost pixel layer will have to
withstand a radiation damage of 2x10 16 neqcm -2 . The current ATLAS pixel detector is based on n + -
in-n pixel sensors which collect electrons. Their radiation hardness up to 2x 10 15 neqcm -2 at a bias
voltage of 600V has already been shown. Recent results obtained with electron-collecting n-in-p
strip sensors [1] suggest that electron-collecting planar sensors might be radiation-hard enough for
the innermost pixel layers at SLHC if bias voltages of beyond 1000V are applied. We have
irradiated n + -in-n sensor assemblies based on the current ATLAS pixel read-out chip FE-I3 to IBL
as well as SLHC fluences using thermal neutrons in Ljubljana as well as protons in Karlsruhe and at
CERN PS and will present first observations of their behaviour after irradiation. Dedicated studies
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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
in a CERN SPS testbeam as well as lab measurements indicate that n + -in-n planar pixel sensors are
fully capable to cope with the radiation damage expected under IBL conditions and might even be
operated at higher fluences.
[1] G. Casse, Presentation at VERTEX2010, http://www.vertex2010.physics.gla.ac.uk
Characterization and performance of Silicon n-in-p Pixel Detectors for the ATLAS Upgrades
Philipp Weigell* 1 , Christian Gallrapp 2 , Alessandro La Rosa 2 , Anna Macchiolo 1 , Richard Nisius 1 ,
Heinz Pernegger 2 , Rainer Richter 3
1 MPI für Physik, Germany
2 CERN, Switzerland
3 MPI-Halbleiterlabor Germany
The existing ATLAS tracker will reach its functional limit at particle fluences of 10 15 neq/cm 2 (LHC).
Thus, for the upgrades at smaller radii like in the case of the planned Insertable B-Layer (IBL) and
for increased LHC luminosities (super LHC) the development of new structures and materials
which can cope with the resulting particle fluences is needed. N-in-p silicon devices are a promising
candidate for tracking detectors to achieve these goals, since they are radiation hard, cost efficient
and don't suffer from type inversion. We present the characterization of the common ATLAS-RD50
p-type pixel production performed by CIS (Erfurt, Germany) on 285µm thick floatzone material.
Single chip modules are built with sensors connected to the current ATLAS front-end chip FE-I3.
The electrical properties of sensors and single chip modules will be shown. They were obtained
with test charge injections, MIPs, and an Am 241 source using the USBPix and the TurboDAQ
system, before and after irradiation with 24GeV/c protons. Besides, an overview of preliminary
testbeam results obtained with these devices will be given.
New 3D-Trench Electrode Si Detectors for Radiation Hard Detectors for SLHC and for X-ray
applications
Zheng Li
Brookhaven National Laboratories, Upton, NY, USA
A new type, US-patent-pending Si 3D electrode detectors, named here as 3D-Trench electrode Si
detectors, is proposed in this work. In this new 3D electrode configuration, one or both types of
electrodes are etched as trenches deep into the Si (about 90% of the thickness, but not all the way
through), instead of all columns as in the conventional 3D electrode Si detectors. With trench
etched electrodes, the electric field in the new 3D electrode detectors are much well defined with no
low or no field regions. Except near both surfaces of the detector, the electric field in the 3D-Trench
electrode Si detectors is nearly cylindrical with no angular dependence in the circular and
hexangular pixel cell geometry, or nearly linear (like the planar 2D electrode detectors) in the case
of parallel plates geometry, all with simple and well-defined boundary conditions. The electric field
in the detector will be reduced by a factor of nearly 10 with an optima 3D-Trench configuration.
The processing is true one-sided with backside un-processed, and the trench etching processing
should be no different than that for the columns used for conventional (standard) 3D electrode Si
detectors. The charge loss due to the dead space associated with the trenches is insignificant as
compared to that due to radiation-induced trapping in SLHC environment. Various new 3D-trench
electrode configurations will be proposed, and electric field simulations will be given. Possible
applications of 3D-trench electrode detectors in X-ray detection will also be discussed.
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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
High efficiency readout circuits for large matrices of pixels
Alessandro Gabrielli, Filippo Giorgi*, Mauro Villa,
INFN, Istituto Nazionale di Fisica Nucleare, Italy
In future collider experiments the increasing luminosity and center of mass energy are rising
challenges in the research field of inner tracking systems, it is crucial to have very fast sensors with
efficient readout in order to sustain the high particle flux. In this context we propose a highefficiency
readout architecture for large binary pixel matrices that is meant to cope with the highstressing
conditions foreseen in the innermost layer of a vertex tracker. We model and design the
digital readout circuits in order to be integrated on a VLSI ASIC. In this work, we considered a
matrix 200x256 pixel wide with a 50µm pitch, for a total area coverage of 1.28 cm 2 . We have
developed an architecture that can sustain a hit rate of 128 MHz distributed on this area. The hits
are latched at pixel level, and the latch is auto-reset after its readout. The matrix readout is
performed on a column data bus, shared among all the matrix rows. It is driven in turn by the
current active column that performs a sweep only over the columns that holds at least one hit. Each
column is read out in one clock cycle independently of the pixel occupancy. The active column
drives the sparsifiers inputs, these components encode and store all the hits into the Barrel which is
a storage element. The barrel is an asymmetric FIFO with dynamic input width. Hits encoding is
optimized for clustered event, the compression algorithm, based on time-order and hits grouping,
can save up to the 45% of the output bandwidth respect to a direct x-y-time encoding. The
architecture is highly parallelized in order to reduce the average pixel dead-time introduced by
readout. Intense simulation campaigns of the architecture pointed out that the readout efficiency is
up to 99.8% using a 50MHz read clock and a time stamp resolution of 300 ns.
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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
Thursday, October 14
Session 4: Development of Ultra Rad. Hard Si detectors
Avalanche effect in Si heavily irradiated detectors: physical model and perspectives for
application
Vladimir Eremin
Ioffe Physical-Technical Institute RAS, SSE, Russia
Abstract_text: The increased signal which has been observed in silicon heavily irradiated detectors
is explained as an avalanche multiplication effect in p-n junction, and the related qualitative model
was proposed in 2009 at 13 CERN-RD50 collaboration workshop. The model is under continuous
development with a target of the quantitative effect explanation and predictions on the detector
operational scenario. The talk gives an overview of the physics of avalanche effect in heavily
irradiated Si detectors in respect of LHC upgrade. The presentation covers the main tasks related
with the detector physics and operation including: • The mechanism of avalanche multiplication in
the deep level rich semiconductors; • The features of steady-state electric field distribution modified
by combination of intensive trapping and avalanching; • The charge transport of nonequilibrium
carriers and signal response of avalanche detectors with deep traps; • Predictions for the detector
characteristics and their modeling. The model which was initially developed for strip detectors is
now extended for the dense pixels arrays.
Development of radiation hard edgeless detectors with current termination structure on ptype
silicon
Elena, Verbitskaya
Ioffe Physical-Technical Institute RAS, SSE, Russia
The TOTEM experiment at LHC demands unique silicon detectors with a minimized insensitive
region width surrounding the stripped active area. The elaborated edgeless detectors with the
insensitive region of 50 um are now successfully employed in the Roman Pots at LHC and exhibit a
stable and expected operation. The upcoming upgrade of the TOTEM facility for higher radiation
limit requires new generation of edgeless detectors operating at fluence up to 1·1015 neq/cm2. The
main stream here is still the development of edgeless detectors with current terminating structure,
which are now processed on the p-type silicon, instead of conventional n-type detectors installed in
the LHC experiments. The current results are focused on the properties of the sensitive cut edge
which is a key element of the detectors. The potential distributions along the sensitive edge which
control 2D electric field and the detector current are presented and interpreted in terms of
amorphous silicon layer passivating the cut edge of the detector. The results on the electric field
profiles at the damaged surface demonstrate the impact of silicon bulk parameters on detector
radiation hardness. The performance of n-on-p detectors which requires the junctions separation by
the p-stops will be also discussed.
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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
Development of planar detectors with active edge
Marco Povoli *1,2 , Gian-Franco Dalla Betta 1,2 , Alvise Bagolini 3 , Maurizio Boscardin 3 , Gabriele
Giacomini 3 , Elisa Vianello 3
1 University of Trento, Dipartimento di Ingegneria e Scienza dell'Informazione, Italy
2 INFN Padova, Gruppo collegato di Trento, Italy
3 Fondazione Bruno Kessler, Center for Materials and Microsystems, Trento Italy
The total area of a silicon radiation detector is usually larger than its active area due to the fact that
devices are typically separated from the wafer with the use of a diamond saw. The cutting
procedure introduces defects and cracks along the edges of the detector: in case the electric field
inside the device reaches these defects, a high leakage current can be drawn by the detector.
Therefore, the cutting region must be at several hundreds of micron away from the active area and
this results into a waste of area that could otherwise be active. 3D technology, thanks to the use of
the Deep Reactive Ion Etching (DRIE), allows for the realization of deep trenches around the
devices eliminating the need of the cutting procedure. These trenches can be heavily doped so as to
behave like ohmic contacts. Despite the technological complication introduced in the fabrication
process, the so called “active-edge” can lead to a reduction of the dead area to values in the order of
10-20 micron. Building on the know-how gained in the past years with 3D radiation detectors,
planar detectors with active-edge have been fabricated at FBK (Trento, Italy). Wafer layout
includes pixel, strip, and pad detectors, as well as test structures. In particular, making use of TCAD
simulations, we have designed different sets of test diodes with variable distances between the
outermost biased junction and the active edge and featuring different termination solutions based on
floating rings, in order to investigate the best compromise between dead area and breakdown
performance. From the technological point of view, the active edge has been conceived to be fully
compatible with 3D detector fabrication, i.e., the same DRIE step used for the trench can also be
used for one of the two electrode etching in a full 3D process. At the conference we will report on
the detector design and simulation, technological aspects and selected results from the electrical
characterization of the prototypes.
Performance Characteristics of p+n MCz Si Pad Sensors after Mixed Irradiation: Impact on
Space Charges, Electric Field Distribution using Simulation Approach
Ajay Kumar Srivastava*, Eckhart Fretwurst, Gregor Kramberger
1 Institute for Experimental Physics, University of Hamburg, Germany
2 Institute for Experimental Physics, University of Hamburg,
3 Jozef Stefan Institute, Jamova cesta 39, 1000 Ljubljana
In the frame work of the RD50 Collaboration (sponsored by the European Organization for Nuclear
Research CERN) , a lot of efforts has been made to obtain radiation hard Si sensors for very high
luminosity colliders since 2002 and still work ongoing to choice the intrinsic sensors type for
particle tracking in order to achieve good position resolution, acceptable charge collection (high
signal to noise ratio) with low material budget at SLHC experiment where luminosity will be ten
fold times from the LHC. In mixed irradiations at SLHC, n- MCz Si sensor material is reported as a
good applicant. In order to study the non-homogeneous distribution of space charges and electric
field distribution in mixed irradiated (reactor neutrons+ protons) p+n MCz silicon pad detectors, we
have used synopsys T-CAD commercial device simulation `program 2010.03 for four-level
numerical modeling of mixed irradiation induced deep level traps using microscopic parameters
obtained from experimental measurements. In mixed irradiated n-MCz samples, the compensation
of acceptors due to donors leads to positive space charges distribution and thus decreases of the full
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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
depletion voltage Vfd. Therefore, this is important to determine the effective introduction rate ηeff
(E30K). In this work, we have determined the ηeff of shallower donor deep trap E30 K using SRH
theory calculations for exp. Neff and shown the behavior of space charges and electric field
distribution in the presence of deep traps. The resulting analysis techniques has been validated and
calibrated by means of detailed comparison of the simulation with current-voltage (I-V) and
capacitance-voltage (C-V) experimental measurements carried out on mixed irradiated samples at
RT of 200C (600C 80 min beneficial annealing).
Surface Properties of Si Sensors pre-rad and post-rad
Hartmut F.-W. Sadrozinski
SCIPP, UC Santa Cruz USA
on behalf of the ATLAS ID Upgrade
We present data on the surface characteristics of (mainly p-type) silicon strip sensors pre-rad and
post-rad. In addition to reporting data on the interstrip capacitance and strip isolation, we
concentrate on the understanding of the workings of the punch-through protection (PTP) structure,
which is customarily tested with a DC i-V method. We are using a IR laser signal to simulate beam
loss, and explain the very large voltages which we find on the implant, which are in apparent
contradiction to the DC measurements.
Session 5: Radiation Damage in Silicon
Radiation damage effects in silicon induced by electrons of different energy
Gunnar Lindström 1 , Eckhart Fretwurst* 1 , Alexandra Junkes 1 , Ioana Pintilie 2 , Roxana Radu 1
1 Institute for Experimental Physics, Physics/University of Hamburg, Germany
2 National Institute of Materials Physics, Magurele-Bucharest, Romania
Irradiation on n-type silicon pad diodes had been performed with electrons of different energies (1.5
MeV, 6 MeV and 15 MeV), and were investigated by Deep Level Transient Spectroscopy (DLTS)
and Thermally Stimulated Current (TSC). In parallel standard capacitance-voltage (C-V) and
current-voltage (I-V) characteristics were recorded. The main focus of these studies was the
development of cluster related defects like V3 and the deep hole traps H(116K), H(140K) and
H(152K) depending on the electron energy in comparison to point defects. Also a shallow donor
giving rise to a TSC peak at 30 K (E(30K)) was of special importance. This defect was found in
neutron and more pronounced in 23 GeV proton irradiated devices and is most likely responsible
for the fact that the space charge stays positive after proton irradiation [1]. The observed
microscopic results and development of the macroscopic device properties will be presented and
discussed.
[1] I. Pintilie et.al., Nucl. Instr. and Meth. A 611 (2009) 52
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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
New results on the annealing behaviour of the E4/E5-defect
Alexandra Junkes*, Coralie Neubüser, Eckhart Fretwurst,
Hamburg University, Department of Experimental Physics Germany
This work deals with the bistable configurations of the E4/E5-defect levels, which are known to be
the important current generator after neutrons and charged hadrons irradiation [1]. We studied 300
µm thick n-type diodes made from MCz and FZ-silicon after irradiation with reactor neutrons.
Capacitance-Deep Level Transient Spectroscopy (C-DLTS) as well as Capacitance-Voltage and
Current-Voltage characteristics were performed. E4/E5 is visible in C-DLTS directly after
irradiation and anneals out at 80°C by changing its configuration. The injection of high forward
current reestablishes the E4/E5-configuration, even after high annealing temperatures (e.g. 200°C).
The aim of this study is to obtain optimal parameters for future studies of the E4/E5-defect. For this
reason injection temperature, type of injected charge carriers, duration and value of applied current
pulse were varied.
[1] A.Junkes, D.Eckstein, I.Pintilie, L.Makarenko and E.Fretwurst, NIM A 612 (2010) 525-529.
Edge-TCT measurements with irradiated microstrip detectors
Gregor, Kramberger*, Vladimir Cindro, Igor Mandić, Marko Mikuž, Marko Milovanović, Marko
Zavrtanik
Jožef Stefan Institute, Department of Experimental Particle Physics, Slovenia
The silicon n + -p micro-strip detectors irradiated with reactor neutrons and 200 MeV pions up to the
fluences of >1e16 cm -2 were investigated by using the Edge-TCT technique. The avalanche
multiplication was studied as a function of fluence and applied bias. The charge multiplication
profiles in the detectors were obtained and the multiplication factors were calculated. They were
found to be moderate. At high fluences the significant electric field is established in the whole
detector at voltages far below the full depletion voltage. The effective trapping times were found in
line with expectations based on measurements at low fluences.
Fluence dependent variations of barrier and generation currents in neutron and proton
irradiated Si pin diodes
Tomas Čeponis*, Eugenijus Gaubas, Stanislavas Sakalauskas, Aurimas Uleckas
Vilnius University, Institute of Applied Research, Lithuania
Potential barrier and its stability under irradiation conditions are the essential characteristics in high
energy particle detectors operation. Formation of defects during irradiation near the metallurgic
junction is very probable, and this can be a reason for degradation of diode barrier characteristics.
Therefore, it is important to investigate variations of the barrier parameters in radiation damaged
diodes. Commonly, barrier parameters are examined by combined analysis of current-voltage and
capacitance-voltage characteristics. However, small sinusoidal signal LRC meters employed with
noiseless bias voltage sources are essential. Moreover, in heavily irradiated (Φ>10 14 cm -2 ) diodes
the conventional impedance based capacitance measurement technique becomes limited due to
increased leakage currents caused by radiation induced generation centres. In this work a technique
for barrier evaluation by linearly increasing voltage (BELIV) based on analysis of current transients
measured at reverse and forward biasing is presented. The technique has been applied in diodes
irradiated by penetrative neutrons and 2.7 MeV energy protons varying fluence in the range of 1E12
- 1E16 cm-2. Fluence and temperature dependent characteristics of the diode barrier and diffusion
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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
capacitance as well as of generation current are discussed. Role of microplasma and radiation
clusters within junction and diode bulk is debated.
Test beam results of Current Injected Detectors (CID) irradiated up to 5×10 15 1 MeV neq/cm 2
Jaakko Härkönen 1 , Panja Luukka 1 , Esa Tuovinen 1 , Teppo Mäenpää 1 , Eija Tuominen 1 , Vladimir
Eremin 2 , Leonard Spiegel 3 , Yuri Gotra 3 , Liv Wiik 4 , Michael Koehler 4
1 Helsinki Institute of Physics, Finland
2 Ioffe Polytechnical Institute Russia
3 Fermi National Laboratory USA
4 University of Freiburg Germany
Both p and n-type magnetic Czochralski silicon (MCz-Si) strip detectors, irradiated to S-LHC
fluencies were tested with 225 GeV muon beam in the CERN H2 area. The AC-coupled 16 cm 2
detectors have 768 strips and a thickness of 300 µm. The pitch is 50 µm, strip width 10 µm, and
strip length 4 cm. The beam test was carried out using a silicon beam telescope, which is based on
the CMS detector readout prototype components, APV25 readout chips, and Hamamatsu
manufactured strip sensors with 60 µm pitch and intermediate strips. The tested CID detectors were
bonded to the APV25 readout. In the CID concept the current is limited by the space charge. The
injected carriers will be trapped by the deep levels and this induces a stable electric field through
the entire bulk regardless of the irradiation fluence the detector has been exposed to. The steady
state density of the trapped charge is defined by the balance between the trapping and emission rates
of charge carriers (detrapping). Thus, the amount of charge injection needed for electric field
stabilization depends on the temperature and the CID sensors were operated in a separate cooling
box capable of providing a -53°C temperature. Results indicate a relative charge collection
efficiency (CCE) at 5×10 15 neq/cm 2 above 30% in irradiated p + /n - /n + CID detector at 600V bias
voltage. At -53°C the signal to noise ration of this CID module was about eight and a forward
current of 30 µA was needed for detector biasing. In standard reverse bias, the same detector could
not provide a sufficiently large signal for particle tracking purposes. A p-type (n+/p-/p+) sensor was
irradiated to a fluence of 2×10 15 neq/cm 2 and measured under same test beam conditions. I accord
with the theory of CIDs developed by the CERN RD39 Collaboration, this detector module could
be biased up to only 230 V due to the lower irradiation fluence. The CCE at 230V was 35% in CID
operation and 20% when reverse biased.
Characterization of low resitivity p-on-n Magnetic Czochralski detectors
Nicola Pacifico* 1 , Michael Moll 1 , Manuel Fahrer 1 , Irena Dolenc 1 , Otilia Militaru 2 ,
LemaitreVincent 2
1 CERN, PH/DT, CH
2 UCL Louvain BE
TCT and CCE studies were performed on pad and strip detectors, produced on a low resistivity
MCz n-bulk (p-side readout). The measurements were performed with a new setup, realized at
CERN in collaboration with the Universite Catholique de Louvain, for multi-technique
measurements on silicon detectors. The obtained results show a good radiation hardness of the low
resistivity n-type bulk.
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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
Poster Session
Investigation of the energy conversion efficiency of nanostructured TiO2 dye-sensitized solar
cells after prolonged irradiation and under thermal stress
Alessandro Cavallaro 1 , Sacha Vaiani 2 , Franco Bogani 1 , Mara Bruzzi 1 , Ennio Carnevale 1,3 , Paola
Paoli 1 , Monica Scaringella 1 , Enzo Perrotta 4 , Patrizia Rossi 1
1 Dipartimento di Energetica, Università di Firenze, I-50134 Firenze (FI), Italy
2 Università di Pisa
3 CERTUS, Università degli Studi di Firenze, Italy
4 Chemper, Signa, Italy
Dye-sensitized solar cells (DSSCs) [1] basically consist of a dye-sensitized nanocrystalline
titanium dioxide (TiO2) film, a redox couple and platinum-covered counter electrode placed inbetween
two TCO glasses. In the recent past they have been addressed as a promising third
generation of solar photovoltaic devices due to their potential low-cost of manufacturing, no
pollution to the environment, high level of integration in buildings. Detailed investigations of the
ageing effects on DSSCs performances are crucial to assess their potential as a practical alternative
to present Si-based photovoltaic devices. In our study a colloidal system withTiO2 nanoparticles
(made by Solaronix, containing about 11 % wt. nanocrystalline titanium dioxide mixed with
optically dispersing anatase particles 13/400 nm, Ti-Nanoxide D) is used for the preparation of
DSSCs. A temperature-dependent X-ray powder diffraction (XRPD) analysis was performed in
order to verify if and how the temperature influences the crystallographic phase-composition of the
nanocrystalline TiO2. The conversion efficiency of the assembled cells are characterised through
both a direct illumination with a sun tracker system and in laboratory by means of a sun simulator
apparatus based on a 550 W Xenon Arc lamp able to produce an irradiance up to 3 Suns. The
energy conversion efficiency is measured as a function of the time of exposure to solar radiation
and after selected isochronal annealing cycles to study possible aging effects on the DSSCs. Results
are presented and discussed.
[1] B.O. Regan, M. Graetzel M Nature 353, 737 (1991)
Exploration of the Mechanism of Charge Collection Induced by Ion Strike in SOI NMOS
Transistors through 3D Simulation
Xiaochen Zhang*, Suge Yue, Liang Wang
Beijing Microelectronics Technology Institute, No.1 Designing Department, China
Introduction Because of the buried oxide layer and the relatively thinner silicon layer, the
generated and collected charge volumes in SOI device are smaller during strike than those of
bulk device, thus SOI technologies are considered to be more resistant to radiation, especially to
single event upset (SEU) than the bulk silicon technologies. But the parasitic bipolar transistor,
inherent to the structure of SOI transistors, can amplify the charge volume in the device and
reduce the SEU hardness of SOI ICs. In SOI NMOS devices, the parasitic bipolar is triggered by
a particle strike when the source/body junction is forward biased due to the accumulation of
holes in the body, leading to electron injection from source to body and amplified charge
collection of drain. This phenomenon is more severe in the floating body case. The
amplification of parasitic bipolar transistor in SOI devices is an important mechanism to
determine the single event upset (SEU) sensitivity. Usually the body contact is an effective way
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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
to reduce the parasitic bipolar effect. The voltage applied to the body contact fixes the body
potential and prevents the source/body junction being forward biased. As was known before, the
body contact structure can mitigate but can not eliminate the amplification of the parasitic
bipolar effect, but recently it has been reported that no bipolar amplification effect was observed
in small feature-sized SOI technologies, such as 0.13µm and 70nm [1],[2]. But in most papers,
the reason for this phenomenon is not that detailed and specific. In this paper, several sets of
transistors have been compared and analyzed, and the effect of parasitic bipolar transistors in
partially depleted (PD) SOI NMOS devices is presented clearly through the transient current
and charge collection induced by heavy ion strike. 3D simulation is applied to study the device
behaviours of the SOI technology, and Davinci is chosen as the TCAD 3D simulator. The 3D
simulation result shows how the ion strike location, the structure (with or without body contact)
of the device, and the energy of striking ion affect the parasitic bipolar gain. The highlight of the
paper lies in the discovery and analysis of charge collection amplification absence. In fact,
although no bipolar amplification is observed at last, there is still parasitic bipolar element
turned on for a short duration. In addition, the electrons in the device are not all collected by
drain (also by source), and this mechanism reduces the charge collection by drain and no bipolar
amplifying is observed if treating the charge collection result macroscopically. II. Simulation of
the Influence of Strike Location The technology applied in the 3D simulation is a 0.13µm
partially depleted (PD) SOI technology. The thickness of the top silicon layer is 100nm, and the
thickness of the gate oxide is 1.8nm. In this simulation, all of the devices are of the same size
0.6µm/0.13µm, and one end of the body in each device is connected to an external contact. All
the devices are on OFF state with a reverse drain/body junction: source, gate and body are fixed
to the ground, and the drain voltage is set as supply voltage, 1.2V. Also, the drain is connected
to a resistance in serial with a capacitance. The LET value of the heavy ion is taken to be
constant along the track in the top silicon layer, with a value of 4MeV•cm2/mg, with a
characteristic 1/e radius of 0.05µm. The ions strike the devices vertically through the device.
According to the experience that body region under gate is one of the sensitive regions of SOI
device, the devices are strucke by heave ions in the middle of the device along the channel
length direction, but each device’s strike location is different along the channel width direction.
The strike locations are 0.15µm, 0.3µm and 0.45µm away from the body contact, respectively.
In this paper, a charge collection gain is applied to evaluate the parasitic bipolar amplifying
effect [3]. The charge collection gain β is defined as the ratio of charge collected by drain (QD)
to the charge collected by body (QB), β= QD / QB. When β>1, there is charge amplification
existing, caused by the parasitic bipolar transistor, and the portion of the drain collection
exceeding the collection by body contact is just due to the electron injection from source into
body. The simulation result shows that the body collections of the devices are very approximate,
but the drain collections are quite different. The device of strike location nearest to body contact
(0.15µm) has a drain collection of 5.8fC and a collection gain of 1.18, while the one of strike
location most far away from the location (0.45µm) has the two values of 12.3fC and 2.62. For
the one with the strike location of 0.3µm, the drain collection is 11fC and the gain is 2.2. The
analysis of the transient current shows that the device, with the distance of 0.15µm from strike
location to the body contact, has a larger maximum body current, less electron injection from
source and a shorter transient duration than the ones with longer distance. Although the body
charge collections of the devices are nearly the same, but the larger body current of the former
device, due to the short distance between the strike location and body contact, can speed up the
evacuation of the holes in the body, thus the potential drop of the body. This shortens the
duration and the amount of the electron ejection from source to body, leading to an earlier
accomplished of drain collection and a smaller volume of drain collection than in the devices
with longer distance between strike location and body contact. III. Simulation of Different
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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
Structures In this part of simulation, three devices of different structures are involved. All of
them are of the same size: 0.6µm/0.13µm. But one device has a float body, and the bodies of the
other two devices are connected to external contacts at one end (1BC) and at both two ends
(2BC), respectively. The location of ion strike is right the centre of the gate for the three devices.
The ion has a same LET value of 4MeV•cm2/mg, but a higher energy, with the 1/e radius 0.2µm.
For the float one, the charge collection gain is defined as the ratio of QD to the charge generated
(QG) during the strike (actually the charge deposited in body. So this is just an approximation,
but less charge volume is deposited in body than the total generation, so the gain in the list is
smaller than that in fact). The drain collections of the three devices are 110fC, 7fC and 4fC,
respectively, and collection gains of 17.8, 1.63 and 0.91. The result shows that body contact
lowers both the charge collection and gain. And in the 2BC situation, no charge collection gain
is observed, QD is smaller than QB, just like the result in [1]. The mechanism of the charge
collection in 2BC device can be concluded as following. The parasitic bipolar in the SOI NMOS
device can be treated as a set of distributed bipolar elements. In the case of a heavy ion strike,
the distance between the body contact and the strike location determines which elementary
bipolar will be triggered. In a short feature sized technology, the device channel is actually
narrower than the ion strike itself. Part of the generated charge is therefore deposited in the
heavily-doped source and drain regions where it is not collected, and the potential of the body
may not rise obviously, especially in the body contact case. Actually in the 2BC device, even
though no collection gain is observed, the element bipolar at the strike location (where the high
density of electron-hole pairs are injected), is still turned on due to the raised potential by the
local high density holes. So around the strike location, there are electrons injected from source
to body, which was observed in the simulation indeed (figure will be shown in full paper). But
this will not last long because holes’ drift movement to the body contacts lowers the body
potential thus the electron injection from source into body. Moreover, even the source collects
electrons in the last phase of charge collection (shown in the way of the positive current), then
the drain may collect less charge than the collection when electron injection doesn’t happen (i.e.,
element bipolar is not turned on), and no parasitic bipolar amplification is observed
macroscopically. Electron collection of source doesn’t happen in the float and 1BC structure, so
the bipolar amplification can be observed clearly. IV. the Influence of the Ions’ Energy In the
1BC case with strike location 0.3µm away from body contact, the drain collection is 11fC with a
collection gain of 2.2 for the 0.05µm 1/e radius, while the two values are 7fC and 1.63 for the
0.2µm 1/e radius. This result shows that in the case of the ion with same LET but higher energy,
the charge collection and the collection gain are both lower. High energy ions might result in a
lower rate of single event effects as is simulated for single transistors. But for the integrated
circuits, the large range of the ion strike may affect more than one device and cause more
complicated effects, leading to a more severe vulnerability to SEU. V. Conclusions In this paper,
the mechanism how the ion strike location, the device structure (with or without body contact),
and energy of striking ion affect the charge collection and parasitic bipolar amplification is
studied. The most important work is the discovery and analysis of the observed charge
collection amplification absence: the short duration of the electron injection from source and the
electron collection of the source reduce the charge collection of drain.
[1] V. Ferlet-Cavrois, P. Paillet, and M. Gaillardin, IEEE Trans. Nucl. Sci., vol. 53, no. 6, pp
3242-3252, Dec. 2006
[2] P. E. Dodd, M. R. Shaneyfelt, J. A. Felix, and J. R. Schwank,, IEEE Trans. Nucl. Sci., vol.
51, no. 6, pp. 3278-3284, Dec.2004.
[3] O. Musseau, V. Ferlet-Cavrois, J. L. Pelloie, et al., IEEE Trans. Nucl. Sci., vol. 47, pp.
2196-2203, Dec. 2000.
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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
Defect Reactions in eletron and ion irradiated p-type silicon
Leonid Makarenko* 1 , Michael Moll 2 , Feodor Korshunov 3 , Stanislav Lastovski 3 , Leonid Murin 3
1Belarusian State University, Department of Applied Mathematics and Computer Science Belarus
2CERN, Department of Experimental Physics, Switzerland
3SPMRC Scientific-Practical Materials Research Centre of NASB, Laboratory of Radiation Effects,
Belarus
There is a good consistency between the experimental data on the behavior of isolated vacancies in
silicon obtained by different groups. However, there is no such consensus on properties of selfinterstitials
and Frenkel pairs in silicon. Furthermore, there is a similar lack in understanding the
divacancy formation mechanism. In this work we present some new findings on the behavior of
self-interstitial atom and divacancies in p-type silicon irradiated with 6 MeV electrons and alphaparticles
of Pu-239 at temperatures of 78 K and 273-295 K. The samples studied were n+-p
structures with different resistivity values in the range 20-4000 Ohm.cm. The processes of radiation
induced defect transformations have been studied using DLTS measurements. It has been found that
divacancy in p-Si irradiated with electrons at cryogenic temperatures is formed during annealing in
a wide temperature range of 120-280 K. This fact suggests that there are several types of metastable
defect structures (generalized Frenkel defects) formed which subsequently are transformed into
divacancies during thermal annealing. This process is enhanced by minority carrier injection. To
monitor the mobile interstitial Si atoms we use the DLTS peaks related to interstitial carbon (H029
peak) and the interstitial carbon-interstitial oxygen complex in its stable and metastable
configurations (H035 peak). We have found that after electron irradiation at LNT the H029 peak
begins to appear only after thermal annealing at temperatures higher than 300 K. The irradiation of
low resistivity silicon with alpha-particles at RT also shows that only a small part of self-interstitials
were trapped by substitutional carbon and the major part of self-interstitials remained immobile at
room temperature. These findings indicate that self-interstitials have a very low mobility even at
room temperature in p-Si. Experimental evidences will also presented that becoming more mobile
under forward current injection the self-interstitials change their charge state to a less positive one.
Carrier drift and diffusion characteristics of Si pin detectors measured in situ during protons
irradiation
Tomas Čeponis*, Eugenijus Gaubas
Vilnius University, Institute of Applied Research, Lithuania
Carrier drift and diffusion parameters determine the functional characteristics of high energy
particle detectors. Evaluation of radiation damage mechanisms is commonly implemented by
combining several techniques based on examination of leakage currents, of thermal stimulated
currents, of capacitance and of drift current transients measurements after irradiation. However,
these techniques become limited at high irradiation fluences (F>1E15 cm-2) when formation of
clusters becomes dominant and concentration of radiation defects significantly overpasses the
density of dopants. Moreover measurements, carried out after irradiation, do not provide the direct
information concerning evolution of defects in the material. In this work, a technique for in situ
control of the parameters of carrier recombination, drift and diffusion during protons irradiation is
presented. Different diode biasing and pulsed excitation modes have been employed to measure the
charge drift and charge collection currents. Evolution of the charge collection transients during 8
MeV protons irradiation is illustrated. Results on charge collection current measurements performed
on magnetic Czochralski grown Si pin diodes are analysed. Impact of the radiation defect clusters
on the carrier recombination, diffusion and drift parameters evaluated by this technique is discussed.
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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
Simulation of Displacement Damage for Silicon Avalanche Photodiodes
Adnan Kilic* , Ercan Pilicer, İlhan Tapan, Emin N. Ozmutlu
Uludağ University, Department of Physics, Turkey
Silicon avalanche photodiodes (APDs) will be exposed to a neutron fluence of about 2.10^13 n/cm2
1 MeV neutron equalevent fluence after 10 years of CMS operation in the ECAL barrel at
CERN.High neutron fluences can interact and cause significiant damage to silicon crystal
lattice.Thus, silicon bulk damage can result in changing the electrical properties and deterioration of
the device.The NonIonizing Energy Loss (NIEL) scaling hypothesis of bulk damage which is the
claim that changes of electrical properties are proportional to NIEL.In this scaling, for convenience,
a given fluence of particles is done by finding the equilavent fluence of 1 MeV neutrons which
would give rise to the same damage. In this study, the primary knock-on atoms (PKA) species
created in APD irridiated by 1 MeV neutron fluences, and displacement damage and NIEL caused
by the recoils in the APD as a function of the neutron fluence during 10 years CMS operation are
carried out using Geant4.
Performance studies of the p-spray/p-stop implanted Si sensors for the SiD detector
Pooja Saxena
University of Delhi, Department of Physics & astrophysics, India
For future lepton colliders, like International Linear Collider (ILC), Silicon Detector (SiD) is one of
the proposed detector. In the innermost vertex of the ILC, Si micro strip sensors will be exposed to
the neutron background of around 1 - 1.6 x 10 10 1-MeV equivalent neutrons cm-2 year-1. The p + nn
+ double-sided Si strip sensors are supposed to be used as position sensitive sensors for SiD. The
shortening due to electron accumulation on the n+n- side of these sensors leads to uniform
spreading of signal over all the n+ strips and thus ensuring good isolation between the n+ strips
becomes one of the major issues in these sensors. One of the possible solutions is the use of floating
p-type implants introduced between the n+ strips (p-stops) and another alternative is the use of
uniform layer of p-type implant on the entire n-side (p-spray). However, pre-breakdown microdischarge
is reported because of the high electric field at the edge of the p-stop/p-spray. An
optimization of the implant dose profile of the p-stop and p-spray is required to achieve good
electrical isolation while ensuring satisfactory breakdown performance of the Si sensors.
Preliminary results of the simulation study performed on the n+n- Si sensors having p-stop and pspray
using device simulation program, ATLAS, are presented.
Solar UV radiation monitoring in Tuscany with a SiC photo-detector system
Emilio Borchi 1 , Renzo Macii 1 , Mara Bruzzi 2,3 , Monica Scaringella 2
1 Fondazione Osservatorio Ximeniano, Firenze Italy
2 Dipartimento di Energetica, Via S. Marta 3, 50139 Firenze, Italy
3 CERTUS, Università degli Studi di Firenze, Italy
Last decade has been characterised by an ever increasing interest directed towards the effective
monitoring of solar UV radiation. It is well known that, even if small amounts of UV radiation are
beneficial to people, playing an essential role in the production of vitamin D, overexposure to UV
radiation is responsible for major public health problems as skin cancer and cataract. A correct
evaluation of the solar UV irradiance as a function of the radiation wavelength and thus of the UV
index in different atmospheric/climatic/geographic conditions is therefore of straightforward
importance. Referring in particular to UV sensing, SiC photodiodes have been proved to be very
interesting, being extremely radiation resistant to UV radiation. Moreover, an advantage of Sic
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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
photodiodes, due to the wide bandgap (4H-SiC 3.2 eV), is that there is no responsivity to IR
radiation, which is important whenever it is desirable to detect UV in an IR background.
A meteorologic station to characterize the UV component of the solar radiation, based on SiC
photodetectors equipped with integrated amplifiers and electronic read-out, has been manufactured
by TECKNA and installed by Osservatorio Ximeniano at several sites in Tuscany (Italy). A
complete characterization of the system has been carried out at Dipartimento di Energetica di
Firenze both with a sun tracker system and in laboratory by means of a sun simulator apparatus
(ABET Technology) based on a 550 W Xenon Arc lamp able to produce an irradiance up to 3 Suns.
Experimental data concern the intensity in UVA and UVB ranges, as well as the UV index, namely
the radiation intensity weighted on the standard CIE erythema action spectrum
[ISO17166:1999/CIE S 007/E-1998]. Data measured during more than one-year of sunlight
exposure in Tuscany are shown, discussed and compared with forecast analyses.
3DISS: DNA on Diamond Dosimeters onboard ISS
A. De Sio a , L. Tozzetti a , M. Bruzzi b , M. Scaringella b , R. Mori b , M. Bucciolini c , C. Talamonti c , E
Woerner d , C. Wild d , Alessandro Donati e , Pierluigi Ganga e , Valfredo Zolesi e and E. Pace a
a Department of Physic and Astronomy, University of Firenze, Largo E. Fermi 2, 50125 Firenze, Italy
b Department of Energetica, University of Firenze, Via S. Marta 3, 50139 Firenze, Italy
c Dip. Clinical Physiopatology, University of Firenze, Viale Pieraccini 6, 50139 Firenze, Italy
d Diamond Materials, Tullastr. 72, 79108 Freiburg, Germany
e Kayser Italia Srl, Via di Popogna 501, 57128 Livorno, Italy
Due to the complexity of the radiation field in space and inside the spacecraft environment, it is
complex to simulate it in laboratory and to reconstruct the actual radiation hazard. The use of tissue
equivalent, biocompatible, offline dosimeters based on diamond substrates allows fabrication of
versatile dosimeters to monitor astronauts, environment and experiments in space. The use of a
semiconductor material let foresee a real time in space read out of the dosimetric information. The
use of inert genetic material (bacteria DNA and RNA) allows integrating (without biological selfrepairing
effects) the real radiation damage suffered due to the radiation environment inside the
spacecrafts. The biocompatibility of diamond allows the fabrication of integrated dosimetric
biological substrate.
The aim of the DNA on Diamond Dosimeters onboard the International Space Station (3DISS)
experiment is to measure the dose absorbed during a space mission on ISS in order to evaluate the
actual genetic damage suffered in space. The experiment will correlate perfectly the biological
damage with the dosimetric measurements because the substrate for the nucleic acids will perform
dosimetric measurements at the same time.
Since the biological damage suffered is a function of the environmental radiation composition, its
correlation with the absorbed dose is not possible to be a priori determined. The 3DISS experiment,
compared also with all the dosimetric information from standards systems or scientific experiments,
will allow the reconstruction of such a correlation.
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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
Friday, October 15
Session 6: Tracker Detectors Upgrades
Campaign to Indentify the Baseline Sensor Technology for the Phase II Tracker Upgrade
Karl-Heinz Hoffmann
Institut für Experimentelle Kernphysik, Karlsruher Institut für Technologie, Germany
On behalf of the CMS Tracker Collaboration
CMS started a campaign to identify the future sensor technology baseline. We ordered a large
variety of 6” wafers in different thicknesses and technologies from HPK. Thicknesses from 50 -
300um are explored on floatzone, magnetic Czochralski and EPI material. The wafers are all
coming in p-in-n and n-in-p versions. P-stop as well as p-spray will be investigated as isolation
technology for the n-in-p type sensors as well as the feasibility of double metal routing on 6” wafers.
Every wafer contains different structures to answer different questions, e.g. geometry, Lorentz angle,
radiation hardness, annealing behavior. Dedicated test structures, diodes, baby sensors, long and
very short strip sensors and real pixel sensors have been designed for this evaluation.
Approximately 1/3 of these wafers were delivered. The contribution will describe the design, the
testing plans and give first results.
Silicon Detectors for the sLHC
Ulrich Parzefall on behalf of the RD50 Collaboration
University of Freiburg, Institute of Physics, Germany
It is foreseen to significantly increase the luminosity of the Large Hadron Collider (LHC) at CERN
by upgrading the LHC towards the sLHC (Super-LHC). Due to the radiation damage limitations of
the silicon detectors presently used, they can not continue to operate at the sLHC. Therefore the
physics experiments will require new tracking detectors for sLHC operation. All-silicon central
trackers are being studied in ATLAS, CMS and LHCb, with extremely radiation hard silicon
sensors to be employed on the innermost layers. Within the CERN RD50 Collaboration, a massive
R&D programme is underway to develop silicon sensors with sufficient radiation tolerance. One
R&D topic is to gain a deeper understanding of the connection between the macroscopic sensor
properties such as radiation-induced increase of leakage current, doping concentration and trapping,
and the microscopic properties at the defect level. We also study sensors from p-type silicon, which
have a superior radiation hardness as they collect electrons instead of holes, exploiting the lower
trapping probability of the electrons due to their higher mobility. A further area of activity is the
development of advanced sensor types like 3D silicon detectors designed for the extreme radiation
levels of the sLHC. These detectors in general have electrodes in the form of columns etched into
the silicon bulk, which provide a shorter distance for charge collection and depletion, which reduces
trapping and full depletion voltage. We will present tests of several detector technologies and
silicon materials at radiation levels corresponding to sLHC fluences. For irradiated detectors from
different manufacturers, we have observed indication of charge-multiplication effects at high bias
voltages, which would increase the signal available after severe irradiation. Based on our results, we
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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
will give recommendations for the silicon detectors to be used at the different radii of sLHC
tracking systems.
Update of the annealing scenario for irradiated silicon p-in-n microstrip sensors
Paul Dervan*, Craig Wigglesworth, Joost Vossebeld, Gianluigi Casse, Antony Affolder, Ashley
Greenall
University of Liverpool Physics UK
The configuration of almost all the silicon microstrip sensors instrumenting the tracker detectors of
the current experiments in LHC is with readout from implanted p-strips on n-type silicon bulk (from
300 to 400µm thick). The performance of these sensor will change with the irradiation and the time
after irradiation (annealing). The effect of the annealing on the performance of the tracking devices
has been a source of concern for the experiments due to the rise of the full depletion voltage with
time. The experiments have anticipated to suppress annealing effects by keeping the sensors at low
temperature also outside operation time. In fact, a scenario that allows a certain amount of
annealing could be advantageous for running the silicon sensors towards the end of the experiment
lifetime when the readout signal starts to be sensitively degraded. A new set of measurement of the
full depletion voltage and charge collection as a function of annealing time with miniature silicon
microstrip sensors is here presented and discussed in view of possible annealing scenarios.
The ATLAS Tracker Upgrade: Radiation Hard Silicon Strip Detectors for the sLHC
Ian Dawson
University of Sheffield England
on behalf of the ATLAS SCT Collaboration
It is foreseen to increase the luminosity of the Large Hadron Collider (LHC) at CERN around 2020
by about an order of magnitude to the sLHC. As the existing silicon tracking in ATLAS (pixel and
strip detectors) is designed to withstand the radiation doses of the LHC only, the tracking detector
(Inner Detector or ID) will need to be replaced. In order to cope with the order of magnitude
increase in pile-up backgrounds at the higher luminosity, an all-silicon tracking detector is being
designed. The new strip detector will use significantly shorter strips than the current Semiconductor
Tracker (SCT) in order to keep the occupancy low enough. As the increased luminosity will mean a
corresponding increase in radiation dose, a new generation of extremely radiation hard silicon
detectors is required. A number of ATLAS R&D projects aimed at developing the sLHC layout of
the ID, silicon sensors with sufficient radiation hardness, radiation-hard front-end electronics, and
readout systems are ongoing to cope with the challenges of higher radiation levels and data rates.
Starting from the projected layout of the ATLAS Tracker Upgrade, we will report on the
achievements of the R&D projects for the upgrade and outline the available options for sufficiently
radiation hard silicon sensors. Recent results from the prototype detectors under study, both before
and after irradiation to sLHC fluences, will be discussed in detail. Concepts for highly-integrated
detector modules, where sensors and read-out electronics get mounted on a light-weight carbon
structure with integrated services will also be shown.
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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
Beam Test Measurements with Planar n-on-p Silicon Microstrip Sensors Irradiated to sLHC
fluences
Liv Wiik* 1 , Michael Köhler 1 , Ulrich Parzefall 1 , Karl Jakobs 1 , Jaakoo Härkönen 2 , Teppo Mäenpää 2
1 University of Freiburg, Germany
2 University of Helsinki, Finland
on behalf of the ATLAS Upgrade Silicon Strip Detector Collaboration
The luminosity upgrade of the LHC to the sLHC will lead to a massive increase in both the
interaction rate and in radiation levels for the tracking detectors close to the interaction point. It is
expected that the innermost strip layers need to withstand fluences of 1x10 15 neq/cm 2 . In order to
cope with these unprecedented radiation levels, novel radiation detectors are essential for the
upgrade. Silicon microstrip sensors in n-on-p technology, named ATLAS07, were designed by the
ATLAS Upgrade Silicon Strip Detector Collaboration and produced by Hamamatsu Photonics. In
this talk results from a beam test conducted at the CERN SPS beamline are presented. The beam
test measurements were taken with both unirradiated and irradiated ATLAS07 sensors. The sensors
were irradiated with protons to fluences of 3x10 15 neq/cm 2 . A main focus of this talk will be on the
resolution of these sensors, their space resolved charge collection, the cross talk behaviour and the
overall charge collection. The measurements were taken with the SiBT beam telescope, which is
based on analogue CMS APV25 readout chips.
Session 7: Diamond Detectors and Devices
Diamond for high energy radiation and particle detection
Harris Kagan
Ohio State University Physics, USA
on behalf of the RD42 Collaboration
Progress in experimental particle physics in the coming decade depends crucially upon the ability to
carry out experiments at high energies and high luminosities. These two conditions imply that
future experiments will take place in very high radiation areas. In order to perform these complex
and perhaps expensive experiments new radiation hard technologies will have to be developed.
Chemical Vapor Deposition (CVD) diamond is being developed as a radiation tolerant material for
use very close to the interaction region where detectors may have to operate in extreme radiation
conditions. During the past few years many CVD diamond devices have been manufactured and
tested. As a detector for high radiation environments CVD diamond benefits substantially from its
radiation hardness, very low leakage current, low dielectric constant, fast signal collection and
ability to operate at room temperature. As a result CVD diamond now has been used extensively in
beam conditions monitors as the innermost detectors in the highest radiation areas of e+e- colliders
(BaBar and Belle experiments) and hadron colliders (CDF and every experiment at the recently
commissioned CERN Large Hadron Collider). In addition, CVD diamond is now being considered
as a sensor material for the particle tracking detectors closest to the interaction region where the
most extreme radiation conditions exist. We will present the present state-of-the-art of
polycrystalline CVD diamond and the latest results obtained from detectors constructed with this
material. Recently single crystal CVD diamond material has been developed which resolves many
of the issues associated with polycrystalline material. We will also present recent results obtained
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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
from devices constructed from this new diamond material. Finally, we will discuss the use of
diamond detectors in present and future experiments and their survivability in the highest radiation
environments.
Diamond growth structural defect removal strategy for radiation detectors fabrication
Volpe Pierre-Nicolas* 1 , Tranchant Nicolas 1 , Arnault Jean-Charles 1 , Pernot Julien 2 , Saada Samuel 1
Pomorski Michal 1 , Tromson Dominique 1 , Soltani Ali 3 , Bergonzo Philippe 1
1 Commissariat à l'Energie Atomique – CEA LIST / Diamond Sensors Laboratory, France
2 Institut NEEL,, CNRS and Université Joseph Fourier, Nanosciences, France, 3
3 Institut d’Electronique et de Microélectronique-IEMN, France
Diamond as wide band gap semi-conductor ( Eg = 5.5 eV) is a very promising material for radiation
detectors because of its radiation hardness, high thermal conductivity and RT carrier motilities of
2000 and 1000 cm 2 /Vs for holes and electrons respectively. However the development of radiation
detectors necessities the achievement of high crystalline quality (CQ) and high purity diamond
layers in order to minimize signal losses due to the electron-hole pair recombination on impurities
and extended crystallographic defects (CD). The first aim of this study is to grow by MPCVD, low
boron doped (LBD) or intrinsic diamond layers with a high CQ either using low [B]/[C] ratios or
feeding small amount of oxygen during growth as already reported. Our second motivation
concerns the production of diamond detectors with optimal Schottky contacts giving high rectifying
ratios from 7 to 10 decades, very low leakage current as well as good Schottky junction properties.
It will be shown that the HPHT substrate polishing induced defects (PID) and substrates bulk
defects can have very detrimental consequences on the diamond layers CQ. Influence of plasma
pre-treatment of the substrate (Ar/O2 plasma or Ar/Cl plasma) will be show by AFM, SEM and
cathodoluminescence (CL) measurements performed on low boron doped diamond layers grown on
etched and unetched Ib (100) HPHT diamond substrates. We also confirmed that an attention has to
be paid on the etched surface topography in order not to induce, during growth, CD which could
have detrimental effects on carrier transport properties. We will show two ways to optimise CVD
diamond layers purity and CQ by a well mastering of the MPCVD growth conditions. The layers
CQ, contaminants level and transport properties have been characterized by SIMS, low temperature
CL and Hall Effect analysis. Finally we will discuss about the way to produce optimal Schottky
contacts on diamond layers for the fabrication of radiation detectors. We will especially insist on the
choice of the Schottky metal and the surface treatment needed to be done before metal deposition. It
will be shown that good Al and Au Schottky contacts can be synthesized on LBD layers with
optimal Schottky junction properties and J(V) characteristics with no generation-recombination
current and high reverse blocking voltages up to several hundred volts.
Laser processing of Silicon-On-Diamond: experimental results and perspectives
Stefano Lagomarsino 1 , Giuliano Parrini 1 , Silvio Sciortino* 1 , Margherita Citroni 2 Federico Gorelli 2
Mario Santoro 2 , Marco Bellini 3 Gabriele Ferrari 3 , Maurizio Vannoni 3 , Luca Berdondini 4
1 INFN, National Institute for Nuclear Physics, Unit of Florence, Italy
2 LENS, European Laboratory for Non-Linear Spectroscopy, Italy
3 INO National Institute of Optics, Unit of Florence, Italy
4 IIT, Italian Institute of Technology, Neuroscience and Brain Technologies , Nanophysics, Italy
Silicon-On-Diamond material has been recently proposed for the implementation of integrated
detectors and biosensors [S. Lagomarsino, G. Parrini, S. Sciortino et al. Appl. Phys. Lett. 96,
031901 (2010)]. Diamond performances, as active material for particle and XUV detection, are
intensely investigated, moreover its favourable electrochemical properties and biocompatibility
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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
makes it very appeling to interface biological neural networks. As discussed in a previous
work[http://pos.sissa.it/archive/conferences/098/029/RD09_029.pdf], the most challenging issues to
reach these goals are the capability of drilling Through Silicon Vias to link the silicon processing
electronics to the active diamond material and, as far as the biosensor is concerned, the capability of
writing conductive graphitic columns into the diamond bulk. The conductive channels are supposed
to link the silicon vias to the diamond surface hosting living cells, through the whole diamond
thickness. These two processes can be performed by pulsed laser irradiation. Since graphite is not as
biocompatible as diamond the graphite columns should not contact the cells, but end very close to
the diamond functionalized surface, which can be made locally conductive by ion implantation. In
this work we present recent progress on the Silicon-On-Diamond material preparation. Moreover,
we report on preliminary works aimed to grow Through Silicon Vias in the silicon side of the
material, graphitic channels in the diamond bulk and ohmic contacts on the diamond surfaces. The
radiation used ranges from near infrared to sub-bangap UV, the pulse widths from the domain of
tens of nanoseconds to that of hundreds of picoseconds. The obtained results are presented and
discussed.
Laser processing of Silicon-On-Diamond: theoretical insights
Stefano Lagomarsino, Silvio Sciortino, Giuliano Parrini,
INFN National Institute for Nuclear Physics, Unit of Florence, Italy
Silicon-On-Diamond material has been recently obtained by sub-diamond bandgap laser irradiation
of the silicon-diamond interface [S. Lagomarsino, G. Parrini, S. Sciortino et al. Appl. Phys. Lett. 96,
031901 (2010)]. Spectroscopic and microscopic techniques have been useful tools for the
comprehension of the processes occurring at the transparent-opaque interface during pulsed
irradiation, but the optimization of the technique, in order to obtain thinner damaged layers, requires
theoretical modeling of the light-matter energy transfer and of the phase transformations occurring
in the materials, for whichever pulse-width, energy density and wavelength. A finite-element model
of the various processes occurring at the diamond-silicon interface was developed, taking into
account light-matter energy transfer, electron-hole plasma generation, diffusion and energy
relaxation to the atoms, temperature-pressure fields and phase transformations. Energy density
thresholds for diamond-silicon bonding were found at several wavelengths and pulse width, along
with an evaluation of the thickness of the damaged layers which resulted in good agreement with
the electron microscopy observations. The model can be easily adapted to the simulation of the
irradiation of any transparent-opaque interface. In particular, the diamond-graphite interface is of
great interest for future applications in which graphite columns have to be grown in diamond for the
implementation of 3D diamond detectors or for electrical contacts with living cells through the
diamond bulk.
Charge Collection Efficiency Mapping of a CVD diamond Schottky Diode
Jacopo Forneris 1 , Alessandro Lo Giudice 1 , Claudio Manfredotti* 1 , Marco Marinelli 2 , Enrico
Milani 2 , Paolo Olivero 2 , Federico Picollo 1 , Giuseppe Prestopino 3 , Alessandro Re 1 , Gianluca
Verona-Rinati 1 , Claudio Verona 2 ,Ettore Vittone 1
1 University of Torino, Exp. Phys. Dept. and INFN, Italy
2 University "Tor Vergata" Rome Dipartimento di Ingegneria Meccanica Italy,
3 Associazione EURATOM-ENEA sulla Fusione Nucleare, Italy
The Ion Beam Induced Charge (IBIC) technique in lateral configuration was used to map the charge
collection efficiency (CCE) of a Schottky diamond radiation detector developed at the “Tor
Vergata” Rome University. The active region was a nominally intrinsic 22 um thick homoepitaxial
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8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
single crystal diamond deposited by MWCVD on a heavily B-doped layer grown on a HPHT
diamond substrate. The p+ buffer layer was used as a ohmic back electrode, whilst the Schottky
electrode was realised by the deposition of a 200 nm thick Al electrode on the diamond frontal
surface. The sample was cleaved and the cross section was irradiated with a focused 2 MeV proton
beam at the microbeam facility of the Legnaro Laboratory (I). The synchronous acquisition of the
position of the ion microbeam raster-scanned on the cleaved surface with the charge pulse induced
at the Schottky electrode, allowed CCE m spatial resolution at differentµmapping to be performed
with a 2 reverse bias voltages. These CCE maps clearly show the formation of the depletion layer
and its evolution as function of the applied bias voltage. Pulse spectra generated in this region show
a median CCE close to 100%, with a spectral resolution of 1.7%. Beyond this high efficiency region,
when pulses are collected in correspondence to the carrier generation in the neutral region, the
median collection efficiency rapidly decreases and the pulse spectra show much broader profiles.
These facts indicate the dominant role played by diffusion in the pulse formation, as it was
confirmed by numerical and Monte Carlo simulations based on models developed from the
Shockley-Ramo-Gunn’s theory. The suitability of this device for nuclear radiation detection or for
dosimetry were validated by an exhaustive electrical characterization both in terms of its transport
properties, through the measurement of the mobility x lifetime product, and from its electrostatic
properties, through the precise definition of the active region extension.
Session 8: Medical Applications
PRIMA: an apparatus for medical application
Valeria Sipala
University of Catania, Department of Physics and Astronomy, Italy
Istituto Nazionale di Fisica Nucleare, Catania, Italy
on behalf of the PRIMA collaboration
In recent years the PRIMA (PRoton IMAging) collaboration has developed a proton radiography
prototype for application in hadron therapy treatments. The apparatus consists of a silicon tracker
with four x-y planes and a calorimeter. Using this system it is possible to estimate the Most Likely
Path (MLP) of a single proton in the matter thus obtaining a good spatial resolution (about 1mm)
and an electronic density resolution (about 1%) within clinical demands. The single particle
tracking approach helps to substantially reduce the Multiple Coulomb Scattering (MCS) problem.
The prototype was completed and the first radiography images were produced. The apparatus
design will be presented and the results obtained will be shown.
Single crystal CVD diamond for conventional and novel therapy techniques
Dominique Tromson 1 , Monika Rebisz-Pomorska 1 , Nicolas Tranchant* 1 , Fabien Moignau 2 , Aurélie
Isambert 3 , Philippe Bergonzo 1
1 CEA, LIST DCSI-LCD, France
2 CEA LNHB France
3 IGR France
Recent developments of new therapy techniques require new detectors to precisely determine the
delivered dose. We developed in our laboratory single crystal CVD diamond (SCDD) growth to use
these synthetic diamonds as dosimeters. In parallel we worked on the packaging of our detectors to
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October 12-15, 2010
use them as dosimeters in clinical environment. Growth optimization and reproducibility allowed us
to achieve detectors with mobility higher than 2500cm 2 .V -1 .s -1 . Connect to these high electronic
properties; we obtain fast and small detectors that could be used in IMRT or stereotactic beams. We
performed clinical environment tests with these dosimeters in order to probe their potentiality. We
first look at the response under Co 60 source irradiation. We measured their signal to noise,
reproducibility and angular dependency. Repeatability and stability has also been studied using a
Varian 6MV accelerator. SCDD dose measurement with IMRT beams was also performed and was
compared respectively to measurement with air ionisation chamber and with the TPS (Treatment
Planning System) calculation. Results obtain on SCDD are very promising because they fulfil the
drastic requirements of the Code of practice as defined by IAEA (International Atomic Energy
Agency) and namely the TRS-398 and the MAESTRO project (Methods and Advanced Equipment
for Simulation and Treatment in Radio-Oncology, 6th FP) specifications. These tests corroborate
the possibility to use small synthetic diamond for mini-beam monitoring and IMRT treatments.
Simulation and characterization of different setups for gamma ray detection using SiPMs and
LYSO scintillators.
Michele Benetti* 1 , Alessandro Tarolli 2 , Gabriele Giacomini 2 , Claudio Piemonte 2
Gian-Franco Dalla Betta 1
1 Universita' di Trento – INFN, DISI - INFN gruppo collegato di Trento sezione di Padova, Italy
2 Fondazione Bruno Kessler Center for Materials and Microsystems Italy
The use of SiPM (silicon photomultipliers) coupled to fast bright scintillators, like cerium doped
silicate based crystals, allows the construction of compact radiation detectors. This type of
assemblies is the subject of deep studies in many fields, in particular it is promising for PET
(Positron Emission Tomography) machines, and have possible application in tracking systems and
calorimeters for High Energy physics and as detector element in gamma ray telescopes. In the past
few years, SiPM devices from several manufacturers have been the object of several studies and it
has been shown that, in a particular assembly, the performance are critically dependent on some
practical setup choices, such as optical grease used as coupling medium, type of crystals and crystal
coatings. These dependences are generally not trivial to identify in the setup design phase. To
understand how different assembly choices might influence the overall performance of the detector
we have performed some preliminary simulation work followed by an experimental activity. In
particular, using a Montecarlo ray-tracing tool, we were able to calculate the distribution of the light
output along the scintillator length. As expected, this distribution is not uniform due to different
efficiency in light collection. Moreover, this dependence can vary with different types of crystal
coating. We also estimated how the light propagates inside the SiPM surface layer structure varying
the angle and the wavelength of the incident light. In this work, we present our approach to the
simulation and the functional characterization of the devices, describing the experimental apparatus
and reporting selected results from the characterization of SiPM prototypes made at FBK (Trento,
Italy) coupled to LYSO scintillators.
Dosimetric Characterization of Synthetic Single Crystal Diamonds for Radiotherapy
Application
ISABELLA CIANCAGLIONI 1 , RITA CONSORTI 2 , FRANCESCO DE NOTARISTEFANI 3 ,
MARCO MARINELLI 1 , ENRICO MILANI 1 , ASSUNTA PETRUCCI 2 , GIUSEPPE
PRESTOPINO 1 , CLAUDIO VERONA 1 , GIANLUCA VERONA RINATI 1 *
1 Università di Roma “Tor Vergata”, Dipartimento di Ingegneria Meccanica, Italy
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8 th International Conference on Radiation Effects on Semiconductor
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October 12-15, 2010
2 Ospedale San Filippo Neri, U.O. Fisica Sanitaria, Italy
3 Università “Roma 3”, INFN – Sez. Roma 3, Italy
The dosimetric properties of a clinical radiation detector based on synthetic single crystal diamond
and fabricated at the laboratories of the University of Rome “Tor Vergata” were studied. The device
was operated at zero bias voltage under irradiation with high energy radiotherapic photon beams (6
and 10 MV). Different square field sizes were considered and the results from our device were
compared to those obtained using a PinPoint and a Semiflex PTW-Freiburg ion chambers. Time
stability of the diamond detector response, its dose and dose-rate dependence were investigated. No
preirradiation procedure was needed and a sensitivity of 0.78±0.02 nC/Gy was measured. Excellent
linearity with dose and dose rate was observed in the 0.03 10 Gy and 100-600 MU/min range,
showing a Fowler correction factor ∆=1.0006 +/- 0.0002. Comparative dose distribution
measurements were performed by means of Percentage Depth Dose (PDD) curves, lateral beam
profiles and output factors in the field sizes range from 0.6×0.6 cm2 up to 10×10 cm2. Particular
care was devoted to the analysis of the response down to the smallest field sizes (≤ 3×3 cm2). Less
than 1% relative deviations were observed in PDD measurements for field sizes between 3×3 and
10×10 cm2, whereas more pronounced variations of 2% and 3% were found for 2×2 and 1×1 cm2
fields, respectively. Narrower lateral beam profiles were measured by the diamond detector with
respect to the PinPoint chamber with an average 90-10% penumbra narrowing of 0.9 mm for the
square field of 2 cm side. Significant differences were found as well between diamond and PinPoint
output factors at 1×1 cm2 field size, in agreement with the well known small field ion chamber
underestimation effect. Finally, the angular and temperature dependence of the diamond detector
response were also studied. The obtained results indicate the investigated diamond based detector as
a low cost high performance clinical radiation dosimeter suitable for the small radiation fields used
in advanced radiation therapy techniques
Session 9: Wide gap semiconductors and devices
AC—coupled pitch adapters for silicon strip detectors
Jaakko Härkönen*,Esa Tuovinen 1 , Teppo Mäenpää 1 , Panja Luukka 1 , Eija Tuominen 1 , Leonard
Spiegel 2 , Yuri Gotra 2
1Helsinki Institute of Physics, Finland
2 Fermi National Laboratory, USA
Silicon strip detector modules that are used in tracker systems of high energy physics experiments
consists of readout hybrid board, the sensor itself and pitch adapter (PA) in between hybrid and
sensor. Modern strip detectors are almost exclusively AC-coupled because of high leakage current
due to the harsh radiation environment. The AC-coupling requires resistive isolation of implanted
strips from the DC-biasing circuit. Strip isolation is commonly realized by integrated poly-silicon
bias resistors, where the resistance value is typically around 1M Ω. We present a novel approach for
implementing the AC-coupling in the pitch adapter. AC-coupled PA's have been processed on
ordinary glass glass wafers. The two layer fan metallization is aluminum and the intermediate
capacitor insulator is aluminum oxide (Al2O3) deposited by the Atomic Layer Deposition (ALD)
method. ALD is self-limiting Chemical Vapor Deposition (CVD) process, which characteristically
results in pinhole-free thin films. The temperature of ALD Al2O3 deposition is 300^0C, thus it is
appropriate for standard glass wafers, which are limited to about 400°C in process steps. The bias
resistors are made on the glass wafer by sputtering tungsten nitride (WNx). The deposition of WNx
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8 th International Conference on Radiation Effects on Semiconductor
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October 12-15, 2010
takes place at approximately room temperature and the resistors are patterned by wet etching with
hydrogen peroxide. The electrical characterization of AC-coupled PA's indicate very good
breakdown performance of the Al2O3 capacitors and homogeneity of WNx resistance values. A DCcoupled
n+/p-/p+ strip detector made of p-type Fz-Si and irradiated with protons to a fluence of
3×10 14 neq/cm 2 was attached to the CMS APV readout hybrid with an AC-coupled PA. The strip
detectors size is 4cm × 4cm and it has 768 strips. Our test beam results indicate a signal-to-noise
ratio of 27 for this module.
UV photoconductivity and Thermally Stimulated Currents in nanostructured TiO2 for dyesensitized
solar cells
Riccardo Mori, Alessandro Cavallaro, Franco Bogani, Mara Bruzzi, Paola Paoli, Patrizia Rossi,
Monica Scaringella
Dipartimento di Energetica, Università di Firenze, I-50134 Firenze (FI), Italy
Investigation on the influence of defect states on the electrical properties of nanocrystalline
TiO2 films is strategic in the perspective of increasing the efficiency of dye-sensitized photovoltaic
cells [1] beyond the present values now limited to 11%. Trapping/detrapping mechanisms at
localized states in the TiO2 are responsible of the slow dynamics of the photocurrent response of
this material to illumination [2]. In our study a colloidal system withTiO2 nanoparticles (made by
Solaronix, containing about 11 % wt. nanocrystalline titanium dioxide mixed with optically
dispersing anatase particles 13/400 nm, Ti-Nanoxide D) is investigated. In order to verify if and
how the temperature is able to influence the crystallographic phase-composition of the TiO2
nanoparticles a temperature-dependent X-ray powder diffraction (XRPD) analysis was carried out.
Photoconductivity under illumination with a UV Xe lamp in different atmospheric
conditions have been carried out. Delay time analysis, current vs. temperature characteristics and
thermally stimulated current spectroscopy (TSC) are studied to analyse the defect content in the
nanostructured TiO2 films and the importance of adsorbants. TSC studies performed in low
temperature range 10-250K is in agreement with a model taking into account of an exponential
density of states [2]. Levels with activation energies in the range 0.07-0.9eV have been found.
Photoconductivity and current vs. temperature studies performed in different atmospheric
conditions are in good agreement with a model taking into account of one main trap, one
recombination centre plus the action of scavengers for surface adsorption [3].
[1] B.O. Regan, M. Graetzel M Nature 353, 737 (1991)
[2] J. Nelson, PHYSICAL REVIEW B , 59, 23 1999
[3] J. Nelson et al., Journal of Photochemistry and Photobiology A: Chemistry 148 (2002) 25–31.
Contacts to high resistivity semiconductors
Arie Ruzin
Tel Aviv University, Faculty of Engineering
Contacts are often critical elements in semiconductor devices. In some cases, such as silicon, due to
massive study one can find adequate models and theories for numerous metal and semi-metal
contacts. However, the issue of contacts to wide bandgap semiconductors in general, and to semiinsulating
semiconductors in particular is still rather vague. Preparation of such contacts is often
treated as "black magic", and better understanding and modeling are needed. It is shown by means
of computer simulation that in semi-intrinsic wide bandgap semiconductors, such as detector grade
CdZnTe, the thumb rules of most semiconductor textbooks do not apply. The reason is that most
textbooks use approximations that are valid for extrinsic semiconductors. Specifically it is shown
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8 th International Conference on Radiation Effects on Semiconductor
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that in a Schottky contact configuration under forward bias conditions the main current component
is due to the minority carriers drift. The minority carriers are injected/generated under the Schottky
contact due to the band bending. Such current is limited either by the surface band bending or by
contact recombination velocity (which is often assumed infinite in simplified calculations). Under
reverse bias conditions the devices can be "swept-out", namely the concentration of the "majority"
carriers in the bulk is limited by their concentration at the Schottky contact. When the bands bend
toward "accumulation" at the surface, the contacts are often considered Ohmic. In this case
"reverse" bias conditions cause majority carrier injection which sometimes leads to space-charge
limited current (SLC). In fact, the only true Ohmic contacts are the ones causing no band bending.
With all this in mind, it is clear that deducing the resistivity of the semiconductors from I-V curves
may be ambiguous, if the exact nature of the contacts is not known.
Study of the luminescence features of single-crystal CVD diamonds by means of the Ion Beam
Induced Luminescence (IBIL) technique
Silvia Calusi *,1,2 , Alessandro Lo Giudice 3,4,5 , Lorenzo Giuntini 1,2 , Mirko Massi 1,2 , Claudio
Manfredotti 3,4,5 , Paolo Olivero 3,4,5 , Alessandro Re 3,4,5
1 University of Firenze, Dept. of Physics and Astronomy, Italy
2 INFN-Istituto Nazionale di Fisica Nucleare, Firenze, Italy
3 INFN-Istituto Nazionale di Fisica Nucleare, Torino, Italy
4 University of Torino, Experimental Physics, Italy
5 University of Torino,“Nanostructured Interfaces and Surfaces” Centre of Excellence, Italy
The presence of defects or impurities in diamond creates many levels of either absorption or of
radiative recombination (luminescence centers) in the band gap, which define the optical properties
of the material. The purpose of the present work is to study structure and purity of homoepitaxial
single-crystal CVD diamonds by analysing the light produced by the luminescence centers during
ion beam bombardment, by means of the IBIL (Ion Beam Induced Luminescence) technique.
Moreover, monitoring luminescence during bombardment can provide information on the evolution
of the defect state of the sample. Luminescence decays were observed and the values of the fluence
at half of the starting luminescence intensity (F1/2) were extracted. Only the intensity of one of the
luminescence centers showed a non-monotonic behavior, with an initial growth and a subsequent
decay, maintaining at the highest fluences an intensity significantly higher than that of other centers.
An interpretation model taking into account the ion beam induced damage is proposed to fit with
satisfactory accuracy the evolution of the luminescence of this center.
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8 th International Conference on Radiation Effects on Semiconductor
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Name Surname Institution
1 Matteo Angarano CAEN, Italy
Participants
2 Christian Barth Karlsruhe Institute of Technology, IEKP, Germany
3 Michele Benetti Universita' di Trento – INFN Italy
4 Andrea Bianchi Università degli studi di Milano Dipartimento di Fisica, Italy
5 M.G. Bisogni University of Pisa and INFN, Italy
6
Maria
Assunta Borgia University of California, Davis, Physics Dept., USA
7 Mara Bruzzi INFN and University of Firenze, Italy
8 Marta Bucciolini INFN and University of Florence, Italy
9 Silvia Calusi INFN Firenze, Università di Firenze, Italy
10 Giulia Calzolai INFN Firenze, Italy
11 Antonino Cappello
Scuola di Specializzazione in Fisica Medica, University of
Firenze, Italy
12 Alessandro Cavallaro INFN and University of Florence, Italy
13 Tomas Ceponis Vilnius University, Institute of Applied Research, Lithuania
14 Roberto Cirio Università di Torino and INFN, Italy
15 Carlo Civinini INFN Firenze, Italy
16 Alessandro Cosci Dipartimento di Fisica, University of Firenze, Italy
17 Ian Dawson University of Sheffield, England
18 Antonio De Sio INFN and Università di Firenze, Italy
19 Paul Dervan Dep. Of Physics University of Liverpool, UK
20 Michael Deveaux IKF, Goethe University Frankfurt, Germany
21 Cristina Di Venanzio
22 Annamaria Didona
Università di Roma Tor Vergata Facoltà di Ingegneria, Dip. Di
Ingegneria Meccanica, Italy
Istituto di Fisiopatologia Clinica University of Firenze and
INFN, Italy
23 Dennis Doering Institut für Kernphysik, Goethe University Frankfurt/M, Germany
24 Vladimir Eremin Ioffe Physical-Technical Institute RAS, SSE, Russia
25 Carlotta Favaro Universitaet Zuerich, Physik Institut, Switzerland
26 Virginia Favuzza
Scuola di Specializzazione in Fisica Sanitaria University of
Firenze, Italy
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27 David Fedele
28 Pablo
8 th International Conference on Radiation Effects on Semiconductor
Materials, Detectors and Devices
October 12-15, 2010
Scuola di Specializzazione in Fisica Sanitaria University of
Firenze, Italy
Fernandez-
Martinez Centro Nacional de Microelectronica, IMB-CNM-CSIC, Spain
29 Eckhart Fretwurst Physics Institute for Experimental Physics, Hamburg, Germany
30 Christian Fulcheri
31 Alessandro Gabrielli
Scuola di Specializzazione in Fisica Sanitaria University of
Firenze, Italy
INFN – Bologna and Department of Physics, Univ. of Bologna
Italy
32 Filippo Giorgi INFN, Istituto Nazionale di Fisica Nucleare, Italy
33 Jaakko Haerkoenen Helsinki University, Finland
34 Karl-Heinz Hoffmann
35 Alexandra Junkes
Institut für Experimentelle Kernphysik, Karlsruher Institut für
Technologie, Germany
Hamburg University, Department of Experimental Physics
Germany
36 Harris Kagan Ohio State University Physics, USA
37 Adnan Kilic Uludag University, Department of Physics, Turkey
38 Gregor Kramberger
39 Stefano Lagomarsino
Jožef Stefan Institute, Dept. Experimental Particle Physics,
Slovenia
INFN, National Institute for Nuclear Physics, Unit of Florence,
Italy
40 Zheng Li Brookhaven National Laboratories, Upton, NY, USA
41 Renata Longo University of Trieste and INFN, Italy
42 Leonid Makarenko Belarusian State University, Belarus
43 Claudio Manfredotti INFN and Università di Torino, Italy
44 Marco Marinelli Dip.Ingegneria Meccanica Università Roma Tor Vergata, Italy
45 Roberto Marzeddu
Scuola di Specializzazione in Fisica Medica, Università di
Cagliari, Italy
46 Serena Mattiazzo INFN - University of Padova Department of Physics, Italy
47 Lorenzo Mazzoni Università di Firenze, Italy
48 David Menichelli IBA Dosimetry Group, Germany
49 Marko Milovanovic
Jožef Stefan Institute, Dept. Experimental Particle Physics,
Slovenia
50 Riccardo Mori INFN and University of Florence, Italy
51 Emanuele Pace INFN and University of Florence, Italy
52 Nicola Pacifico CERN Switzerland
53 Paola Paoli University of Firenze, Italy
54 Ulrich Parzefall University of Freiburg, Institute of Physics, Germany
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October 12-15, 2010
55 Iacopo Peruzzi
56 Siri Popule Istituto di Fisica ASCR
57 Marco Povoli
58 Valentina Reggioli
Scuola di Specializzazione in Fisica Sanitaria University of
Firenze, Italy
University of Trento, Dip. Ingegneria Scienza dell'Informazione,
Italy
Scuola di Specializzazione in Fisica Sanitaria University of
Firenze, Italy
59 Patrizia Rossi Dipartimento di Energetica, University of Firenze, Italy
60 Andre' Rummler
TU Dortmund, Lehrstuhl fuer Experimentelle Physik IV,
Germany
61 Arie Ruzin Tel Aviv University, Faculty of Engineering
62 Hartmut Sadrozinski SCIPP, UC Santa Cruz USA
63 Pooja Saxena University of Delhi, Department of Physics & astrophysics, India
64 Monica Scaringella
65 Silvio Sciortino
66 Leonello Servoli INFN Perugia, Italy
INFN and Dipartimento di Energetica, Università di Firenze,
Italy
INFN National Institute for Nuclear Physics, Unit of Florence,
Italy
67 Carla Sini Dip.di Fisica Università di Cagliari, Italy
68 Valeria Sipala INFN Catania, Italy
69 Piero Spillantini INFN Firenze, Università di Firenze, Italy
70 Ajay Kumar Srivastava
Institute for Experimental Physics, University of Hamburg,
Germany
71 Ricardo Sussmann King's College London, London, UK
72 Cinzia Talamonti Dip.di Fisiopatologia Clinica University of Firenze, Italy
73 Ingo Torchiani CERN Switzerland
74 Lorenzo Tozzetti INFN and University of Firenze, Italy
75 Nicolas Tranchant Commissariat à l'Energie Atomique – CEA LIST, France
76 Elena, Verbitskaya Ioffe Physical-Technical Institute RAS, SSE, Russia
77 Gianluca
78
Verona
Rinati
Università di Roma “Tor Vergata”, Dipartimento di Ingegneria
Meccanica, Italy
Pierre-
Nicolas Volpe Commissariat à l'Energie Atomique – CEA LIST, France
79 Philipp Weigell MPI fur Fisik, Germany
80 Liv Wiik University of Freiburg, Germany
81 Margherita Zani Dip.di Fisiopatologia Clinica University of Firenze, Italy
82 Xiaochen Zhang Beijing Microelectronics Technology Institute, China
37