TY  - THES
AU  - Schnedler, Michael
TI  - Quantitative scanning tunneling spectroscopy of non-polar III-V compound semiconductor surfaces
VL  - 44
PB  - RWTH Aachen
VL  - Dr.
CY  - Jülich
M1  - FZJ-2015-05318
SN  - 978-3-95806-075-3
T2  - Schriften des Forschungszentrums Jülich. Reihe Information / Information
SP  - 122 S.
PY  - 2015
N1  - RWTH Aachen, Diss., 2015
AB  - The investigation of non-polar III-V semiconductor surfaces by cross-section scanning tunneling microscopy and spectroscopy as well as transmission electron microscopy revealed physical surface effects that could have a major impact on novel electrical devices, such as light-emitting diodes, lasers, solar cells, but also high-electron-mobility transistors. Furthermore, photo-excited scanning tunneling spectroscopy was performed on non-polar GaAs(110) surfaces. With this promising technique, surface photo-voltages and local charge carrier distributions can be probed with atomic resolution. The general difficulty in a quantitative analysis of scanning tunneling spectroscopy measurements and hence in the determination of physical properties of the semiconductor surface is the $\textit{tip-induced band bending}$: The electrostatic potential of the tip is not completely screened at the surface of the sample, especially for low-doped materials. Hence, the valence- and conduction band edge of these materials are bent to higher or lower values compared to their values deep within the bulk material. Additionally, one has to take into account the generation and the redistribution of light-excited charge carriers for photo-excited scanning tunneling spectroscopy. Thus, in this thesis, a quantitative description of scanning tunneling spectroscopy with and without light-excited carriers is developed. It is based on a finite difference iteration of the electrostatic potential and the carrier distributions in three dimensions, followed by the calculation of the tunnel current that incorporates light-excited carriers. On the basis of this model, the comparison of measured and calculated scanning tunneling spectra enables the determination of the semiconductor's physical properties. At first, the model was applied to scanning tunneling spectra measured on $\textit{p}$-GaAs(110) surfaces with and without laser excitation. It is proven that the model [...]
LB  - PUB:(DE-HGF)11 ; PUB:(DE-HGF)3
UR  - https://juser.fz-juelich.de/record/203365
ER  -