Plenarvorträge - DPG-Tagungen

Halbleiterphysik Mittwoch
bildung der Modenstrukturen wird diskutiert.
HL 32.3 Mi 18:15 H17
Modeling of optical properties for type-II semiconductor
lasers — •Christoph Schlichenmaier 1 , Jörg Hader 2 , Jerry V.
Molony 2 , Angela Thränhardt 1 , Mackillo Kira 1 , and Stephan
W. Koch 1 — 1 Philipps-Universität & Wissenschaftliches Zentrum für
Materialwissenschaften Marburg — 2 Arizona Center for Mathematical
Sciences and Optical Sciences Center, University of Arizona, Tucson,
AZ 85721
Design of advanced semiconductor laser structures demands the insightful
use of compound materials consisting of many constituents.
Smart alignment of heterostructure layers like type-II structures is an
additional way of band gap engineering. Quantum optical modeling of
electron and photon dynamics[1,2] connected with a realistic band structure
explains optical properties and device performance and helps to map
out the parameter space. We discuss gain, α-factors and luminescence for
various systems.
[1] A. Girndt, S.W. Koch, and W.W. Chow, Appl. Phys. A 66, 1 (1998).
[2] M. Kira, F. Jahnke, W. Hoyer, and S.W. Koch, Prog. Quantum Electron.
23, 189 (1999).
HL 32.4 Mi 18:30 H17
Microscopic Modelling of Semiconductor Laser Dynamics
— •Angela Thränhardt 1 , Christoph Schlichenmaier 1 ,
Stephan W. Koch 1 , Jörg Hader 2 , and Jerome V. Moloney 2
— 1 Fachbereich Physik und Zentrum f*r Materialwissenschaften,
Philippsuniversit*t Marburg, Renthof 5, 35032 Marburg — 2 Arizona
Center of Mathematical Sciences and Optical Sciences Center, University
of Arizona, Tucson, Arizona 85721
To predict the optical properties of semiconductor laser structures, a
microscopic treatment of the carrier dynamics is essential. We calculate
the dynamics of semiconductor laser structures, fully including carriercarrier
as well as carrier-LO phonon scattering effects. The dynamics
depends on parameters such as the excitation energy and intensity. We
discuss the detailed dynamics which can only be modelled microscopically
as well as the validity of simple rules of thumb for scattering rates
and temperature of injected carriers.
HL 32.5 Mi 18:45 H17
Microscopic Calculation of Relaxation Times in Semiconductor
Laser Structures — •Sascha Becker 1 , Angela Thränhardt 1 ,
Stephan W. Koch 1 , Jörg Hader 2 , Jerome V. Moloney 2 , and
Weng W. Chow 3 — 1 Fachbereich Physik und Zentrum für Materialwissenschaften,
Philippsuniversität Marburg, Renthof 5, 35032 Marburg —
2 Arizona Center of Mathematical Sciences and Optical Sciences Center,
University of Arizona, Tucson, Arizona 85721 USA — 3 Sandia National
Laboratories, Albuquerque, NM 87185-0601 USA
HL 33 III-V Halbleiter I
In semiconductor laser structures, scattering times were classically obtained
by fits to experiment. Although this allows one to fit experimental
spectra, this “theory” has no predictive capability. A microscopic
inclusion of scattering, on the other hand, is very complex and timeconsuming.
We attempt to remedy this dilemma by extracting effective
scattering rates from a microscopic calculation and using these in a relaxation
time model, obtaining good agreement with a microscopic model
for the general features. We discuss dependencies of relaxation times on
different parameters, e.g. carrier distribution and band structure.
HL 32.6 Mi 19:00 H17
Intersubbandelektrolumineszenz von Quantendrahtkaskadenstrukturen
bei 8.5 µm — •Stefan Schmult 1 , Thomas Herrle 1 ,
Werner Wegscheider 1 , Max Bichler 2 , Dieter Schuh 2 und
Gerhard Abstreiter 2 — 1 Universität Regensburg, Institut für
Experimentelle und Angewandte Physik, 93040 Regensburg — 2 Walter
Schottky Institut, Technische Universität München, Am Coulombwall,
85748 Garching
Basierend auf theoretischen Berechnungen [1] wurden Quantendrahtkaskadenemitterstrukturen
im GaAs/AlGaAs-Heterosystem hergestellt.
Die Herstellung der Quantendrahtstrukturen erfolgte mittels des epitaktischen
Überwachsens von atomar glatten Spaltflächen (CEO). Elektrolumineszenz
wurde bei einer Wellenlänge von 8.5µm bei 20K beobachtet
[2]. Überhalb eines Schwellstroms von 200mA ist die emittierte Leistung
pumpstromabhängig und beträgt bis zu 17nW. Der Vortrag beschreibt
zusammenfassend Design und Herstellung der Quantendrahtstrukturen
und stellt Ergebnisse ihrer elektrischen und optischen Charakterisierung
dar. [1] I. Keck, S. Schmult, W. Wegscheider, M. Rother, A.P. Mayer,
Phys. Rev. B 67, 125312 (2003). [2] S. Schmult, I. Keck, T. Herrle, W.
Wegscheider, M. Bichler, D. Schuh, G. Abstreiter, Appl. Phys. Lett. 83,
1909 (2003).
Zeit: Mittwoch 18:15–19:30 Raum: H14
HL 33.1 Mi 18:15 H14
GaMnAs grown by MOVPE under RAS control — •Alexander
Philippou, Stefan Weeke, Markus Pristovsek, and Wolfgang
Richter — Institut für Festkörperphysik, SFb 296, Technische Universität
Berlin
Under the aspect of spin electronics dilute magnetic III-V semiconductors
are of great interest. In this contribution we report on Mn doped
III-V semiconductors which were grown by metal organic vapor phase
epitaxy (MOVPE). In contrast to Molecular Beam Epitaxy the growth
temperatures are much higher (≥ 500 ◦ C). Thus the need for in-situ control
is even more severe for MOVPE. We used reflectance anisotropy
spectroscopy (RAS) to monitor the doping level and roughness during
growth. We determine the critical layer thickness of GaMnAs and correlate
the results with in-situ ellipsometry and ex-situ x-ray diffraction
studies.
HL 33.2 Mi 18:30 H14
Electronic properties of Carbon and Zinc acceptors in GaAs
studied with Low Temperature Scanning Tunneling Microscopy
— •S. Loth 1 , M. Wenderoth 1 , T.C.G. Reusch 1 , L. Winking 1 ,
R.G. Ulbrich 1 , S. Malzer 2 , and G. Döhler 2 — 1 IV. Physikalisches
Institut, Universität Göttingen, D-37077 Göttingen — 2 Institut für Technische
Physik, Universität Erlangen-Nürnberg, D-91058 Erlangen
The electronic properties of single carbon and zinc acceptors located
near {110} surfaces of GaAs were studied with a low temperature UHV
Scanning Tunneling Microscope at 8K. Zn is a substitutional acceptor
on a Ga site with a covalent radius about 30% larger than the replaced
Ga atom. C on the other side is a substitutional acceptor on an As site
and contracts the bonds to the adjacent Ga atoms by about 15%. In
voltage-dependant constant current topographies (-3V to +4.5V) both
dopants show comparable patterns, with a variety of different contrasts.
The orientation of the features is clearly linked to the exact orientation
of the surface under investigation, i.e. (110) vs. (1¯10). Especially at low
voltages the C as well as the Zn acceptor appear as nearly equilateral
triangular protrusions extended over several nanometers. At higher voltages
the symmetry of the triangle evolves into a prolate shape oriented
along (100).