Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 24: Poster Session: Ge/Si/SiC / III - V Semiconductors
HL 24.5: Poster
Montag, 26. März 2012, 16:00–19:00, Poster D
Influence of dilute amounts of Nitrogen in GaAs - A comparison of simulated and experimental STEM HAADF-Z-Contrast measurements — •Nikolai Knaub1, Andreas Beyer1, Vivien Voßebürger1, Rafael Fritz1, Kakhaber Jandieri1, Markus Heidelmann2, and Kerstin Volz1 — 1Faculty of Physics and Material Science Centre, Philipps Universität Marburg, D-35032 Marburg — 2IFF and ER-C, Research Centre Jülich, D-52425 Jülich
The integration of small concentrations of nitrogen into III-V semiconductors such as GaAs and GaP has a big influence on their band gaps and electronic properties. Therefore dilute nitrides are very interesting for electronic and optoelectronic applications. A high crystal quality is necessary to ensure a high efficiency of these devices.
We used a high-angle annular dark field (HAADF) detector in a probe-corrected scanning transmission electron microscope (STEM) to investigate the influence of nitrogen on the structure of these materials. The small covalent radius of nitrogen compared with gallium or arsenic induces static atomic displacements (SADs), whose influence on the crystal-structure also can be measured by quantitative evaluation of HAADF images. An absorptive potential approximation and crystal input structures with and without SADs have been used for the simulation.
It will be shown, that for the low sample thicknesses used for high-resolution Z-contrast imaging, the absorptive potential approximation is valid and that simulation and experiment are in a good agreement, when we take SADs into account.