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@PHDTHESIS{Portz:829939,
author = {Portz, Verena},
title = {{I}nvestigation of ternary nitride semiconductor alloys by
scanning tunneling microscopy},
volume = {48},
school = {RWTH Aachen},
type = {Dissertation},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
reportid = {FZJ-2017-03543},
isbn = {978-3-95806-232-0},
series = {Schriften des Forschungszentrums Jülich. Reihe Information
/ Information},
pages = {140 S.},
year = {2017},
note = {Dissertation, RWTH Aachen, 2017},
abstract = {In this thesis different lattice-matched
Al$_{1-x}$In$_{x}$N/GaN heterostructures were investigated
with the aim to deduce strain, compositional fluctuations,
defects, and electronic properties on cross-sectional
$\textit{m}$-plane Al$_{1-x}$In$_{x}$N cleavage surfaces.
The electronic properties of
Al$_{1-x}$In$_{x}$N($10\overline{1}$0) surfaces were
investigated by cross-sectional scanning tunneling
spectroscopy in combination with density functional theory
calculations. The calculations revealed empty Al and/or
In-derived dangling bond states at the surface, which were
calculated to be within the fundamental bulk band gap for In
contents smaller than 60\%. For In contents of ${x}$ = 0.19
and ${x}$ = 0.20, the energy of the lowest empty In-derived
surface state was extracted from tunnel spectra acquired on
Al$_{1-x}$In$_{x}$N($10\overline{1}0$) cleavage surfaces to
be E$_{C}$ - 1-82 $\pm$ 0.41 eV and E$_{C}$ - 1.80 $\pm$
0.56 eV, respectively, in good agreement with the calculated
energies. In addition, a polarity dependent Fermi-level
pinning of the surface state was identified. Based on these
results it was concluded, that under growth conditions the
Fermi level is pinned by the In-derived dangling bond state
for In contents smaller than about 60\%. For larger In
contents no Fermi level pinning is present. In order to fit
simulations to the experimentally obtained tunnel spectra,
an average value of the electron affinity $_{\chi AllnN}$ of
3.5 $\pm$ 0.1 eV was necessary. A thorough literature survey
of theoretically and experimentally obtained values of the
electron affinities of GaN, AlN, and InN revealed two
issues. First, a broad range of values was reported for the
electron affinities with deviations of more than 50\%.
Second, [...]},
cin = {PGI-5},
cid = {I:(DE-Juel1)PGI-5-20110106},
pnm = {143 - Controlling Configuration-Based Phenomena (POF3-143)},
pid = {G:(DE-HGF)POF3-143},
typ = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
url = {https://juser.fz-juelich.de/record/829939},
}