ICMCTF 2012! - CD-Lab Application Oriented Coating Development

12:00pm C1-1-7 The deposition of metal oxide coatings for electrocatalytic
and photo-active applications by closed field unbalanced
magnetron sputter ion plating, X. Zhang (xiaoling.zhang@miba.com), K.
Cooke, Teer Coatings Limited, Miba Coating Group, UK, G. Eitzinger,
High Tech Coatings GmbH, Miba Coating Group, Austria, J. Hampshire, Z.
Zhang, Teer Coatings Limited, Miba Coating Group, UK
Metallic oxides coatings, for example, TiO2, are of increasing technological
importance in a wide range of industrially relevant functional surfaces on
components for the renewable energy sector, including the hydrogen
economy. Reactive closed field unbalanced magnetron sputter ion plating
(CFUBMSIP) provides an effective, industrially-compatible processing
route for the deposition of metallic oxides, with controlled composition,
structure, and mechanical, electronic and optical properties.
The current development of TiO2-based CFUBMSIP coatings for
applications is described, including the electrolytic production of hydrogen
(water-splitting - from both direct UV and visible light photo-activity, and
via conventional electrolysis), photo-voltaics (PV) with long-life and low
cost, and photo-catalytic surfaces with anti-microbial properties.
The optical band gaps of the anatase and rutile TiO2 phases result in
excellent optical transmittance in the visible and near infra-red regions.
Stoichiometric TiO2 is also a good dielectric has a high refractive index.
Ultraviolet (UV) light has an energy higher than the band gap (Eg) of TiO2,
resulting in electron-hole pair generation. If such excited electrons or holes
can diffuse to the TiO2 surface they can induce the formation of different
kinds of radicals or ions (and, for example promote the splitting of water
molecules, generating hydrogen and oxygen, or degrading or destroying
biological matter, creating an antimicrobial surface), or the separated charge
carriers can sustain an electrical current (as in a PV device). The intensity of
visible light in the solar spectrum is around 9x that of the UV light
responsible for the photo-activity of TiO2. An efficient process of doping,
e.g. the introduction of nitrogen, carbon or iron etc. into TiO2 can narrow
the band gap and thus shift the coatings optical response from UV to visible
light.
Well crystallised anatase or rutile-phase TiO2 structures will be critical for
the PV cell application. Deliberately increasing the surface area of the thin
film coatings can enhance efficiency in the PV application by increasing the
absorption of optical radiation, and in electrolytic applications by increasing
the density of active sites within a given area.
The production of well crystallised TiO2 thin films by the reactive
CFUBMSIP process is described. Process parameters, including Ar/O2
ratio, heating, and elemental doping have been investigated systematically.
The effects of various dopants, including N, Fe and Mn on the band gap of
TiO2 and the functional properties of the thin films are discussed, as is the
potential for further optimization industrial scale-up.
Fundamentals and Technology of Multifunctional Thin
Films: Towards Optoelectronic Device Applications
Room: Tiki Pavilion - Session C2-1/F4-1
Thin Films for Photovoltaics and Active Devices:
Synthesis and Characterization
Moderator: T. Terasako, Graduate School of Science and
Engineering, Ehime University, Japan, M. Cremona,
Pontificia Universidade Católica do Rio de Janeiro
10:00am C2-1/F4-1-1 The Degradation of TixN1-x/HfO2 p-channel
MOSFETs under Hot Carrier Stress, J.Y. Tsai
(abc_7736@hotmail.com), National Sun Yat-Sen University, Taiwan
This work investigates the hot carrier (HC) effect in HfO2/TixN1-x p-channel
metal oxide semiconductor field-effect transistors (p-MOSFETs).
Generally, the sub-threshold swing (S.S) should increase during HC stress,
since the interface states near drain will be generated under high electric
field due to drain voltage (VD). However, the experimental data exhibits the
S.S decreases under HC stress and the degradation level is dependent on the
concentration of nitrogen in stack gate (TiXN1-X). Besides, the reduction of
threshold voltage (Vth) illustrates the electrons trap in HfO2 layer under HC
stress. This behavior could be attributed to increase in the entire capacitance
due to electron trapping in HfO2 bulk, improving S.S. Furthermore, the C-V
measurement with high and low frequency could detect the defects which
approach HfO2 layer, evidencing the trapping pheromone in this work.
Monday Morning, April 23, 2012 4
10:20am C2-1/F4-1-2 Investigation of Random Telegraph Signal with
High-K/Metal Gate MOSFETs, C.E. Chen (alien_2366@hotmail.com),
National Chiao Tung University, Taiwan
A novel method, called random telegraphy signal (RTS), was constructed to
characterize the gate oxide quality and reliability of metal-oxidesemiconductor
field-effect-transistors (MOSFETs). With the aggressive
scaling of device size, drain current RTS (Id RTS) become a critical role in
carrier transport of MOSFETs. Besides, RTS in gate leakage current (Ig
RTS) was denoted as the other new method to understand property of gate
oxide. Recently, the study of RTS has also been made in MOSFETs with
high dielectric constant and metal gate (high-k/metal gate). However, the
RTS in high-k/metal gate MOSFETs, which is related to hot carrier stress
(HCS), has not previously been studied yet. This paper investigates the
mechanism of HCS in high-k/metal gate MOSFETs and provides a
fundamental physical model.
10:40am C2-1/F4-1-3 Enhancement of Resistive Switching
Characteristics in SiO2-based RRAM by High Temperature Forming
Process, Y.T. Chen (d983090005@student.nsysu.edu.tw), National Sun
Yat-Sen University, Taiwan
Forming process with current compliance (soft break-down) is necessary to
activate the resistive switching behavior for most of the resistance random
access memory (ReRAM). Due to the rich oxygen ions among SiO2 film,
the amount of mobile oxygen ions induced from forming process would
exceed the reserving ability of TiN oxygen reservoir as the thickness of
SiO2 films are too thick. The exceeding mobile oxygen ions will recombine
with the oxygen vacancies in the SiO2 film near the TiN/SiO2 interface and
result in forming fail. Through executing high temperature forming process
(HTF), it improves the forming process by enhancing the amount of mobile
oxygen ions being drove into TiN electrode. Furthermore, the increased
mobile oxygen ions can extra repair the conductive filament and reach
lower off-current during the reset process that has undergone HTF for
activation.
11:00am C2-1/F4-1-4 The Impact of Strain on Gate-Induced Floating
Body Effect for PD SOI p-MOSFETs, W.H. Lo, T.C. Chang
(tcchang@mail.phys.nsysu.edu.tw), C.H. Dai, NSYSU, Taiwan
This work studies the influence of gate induced-floating body effect
(GIFBE) on negative bias temperature instability (NBTI) in strained partial
depleted silicon-on-insulator p-type metal-oxide-semiconductor field effect
transistors (PD SOI p-MOSFETs). The experimental results indicate GIFBE
causes a reduction in the electrical oxide field, leading to a better NBTI
reliability under FB operation. The electron accumulation in the FB can be
partially attributed to the electrons tunneling from the process-induced
partial n+ poly gate. However, based on different operation conditions, we
found the dominant origin of electrons was strongly dependent on holes in
the inversion layer under source/drain grounding. This suggests that the
mechanism of GIFBE at higher voltages is dominated by our proposed
anode electron injection (AEI) model. Moreover, based on this new model,
the mechanical compressive strained operation was further introduced to the
SOI p-MOSFET. It was found that the strained device under FB operation
exhibits a much less NBTI degradation. This behavior can be attributed to
the fact that more electrons accumulation induced by strain effect reduces
the electric oxide field during NBTI stress.
11:20am C2-1/F4-1-5 Plasma deposited ZnO layers for thin film
photovoltaics: synthesis, characterization and growth mechanism, M.
Creatore (m.creatore@tue.nl), Eindhoven University of Technology,
Netherlands INVITED
Due to their wide band gap, transparent conductive oxides ( TCOs) exhibit a
high transparency in the solar spectral range. Therefore, they are used as
transparent electrodes in many applications, e.g. in flat panel displays,
architectural and automotive glazing, solar thermal applications and thin
film solar cells, either (amorphous/micro-crystalline and poly-crystalline)
silicon- or non-silicon based (e.g. CIGS).
In this contribution, the investigation on low pressure plasma-enhanced
chemical vapor deposition (PE-CVD) of poly-crystalline (Al-doped) zinc
oxide layers serving as TCOs in thin film solar cells, is addressed. An
argon- fed expanding thermal plasma where the deposition precursors
(diethylzinc, trimethylaluminum and oxygen) are fed in the downstream
region is used for the deposition of Al- doped ZnO. The presented studies
will highlight the impact of specific plasma and process parameters on the
ZnO:Al nucleation phase, grain development (in terms of crystallographic
orientation and size) and morphological and electrical properties, coupled to
specific demands in thin film solar cell technology, i.e. in terms of band
gap, conductivity and morphology/texturing.
In particular, selected insights will be presented in research areas, where a
multi-diagnostic approach is adopted in order to investigate: