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@PHDTHESIS{Andr:872825,
author = {Andrä, Michael Tobias},
title = {{C}hemical control of the electrical surface properties of
n-doped transition metal oxides},
volume = {60},
school = {RWTH Aachen},
type = {Dissertation},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
reportid = {FZJ-2020-00295},
isbn = {978-3-95806-448-5},
series = {Schriften des Forschungszentrums Jülich. Reihe Information
/ Information},
pages = {X, 150 S., S. XI-XXXVIII},
year = {2019},
note = {RWTH Aachen, Diss., 2019},
abstract = {Novel classes of materials are required to meet the
technological challenges in modern electronics. By
ultimately merging surface physics and band engineering
approaches with the chemistry of complex oxides, oxide
electronics are believed to meet the rapidly growing demands
stemming from the decreasing structure size of electronic
applications. A lot is known about the behavior of complex
oxides in the bulk. Surfaces and interfaces, however, may
show fundamentally varying properties due to the reduced
dimension and short diffusion lengths involved. Thus, the
surfaces of complex oxide semiconductors and especially
their interfaces formed with other complex oxides and metals
are expected to play an even more important role in the
technological progress of the upcoming decades. In order to
pave the way to novel tailored applications, understanding
the redox processes at the complex oxide surfaces is
essential. Within this thesis, state-of-the-art
spectroscopic tools are used that allow for in-situ surface
investigations in varying atmospheres thereby demonstrating
the differences between surface and bulk chemistry and
determine how space charge formation couples the surface
chemistry and the electronic properties. By the utilization
of ambient pressure photoelectron spectroscopy the previous
experimental limitations of an undefined surface state and
contamination that occurred due to the $\textit{ex-situ}$
transport of samples. The spectroscopic results determined
on $\textit{n}$-SrTiO$_{3}$ single crystals and thin films
clearly demonstrate the $\textit{p}$O$_{2}$-dependent
activation of the strontium sublattice at intermediate
temperatures that is accompanied by a shift of the Fermi
level from the conduction band edge into the band gap. This
shift illustrates an electron depletion layer being present
at the $\textit{n}$-SrTiO$_{3}$ surface and thus the
formation of a surface space charge layer. These findings
are substantiated by electrical characterization of the
surface contact and the $\textit{in-plane}$ sheet properties
in Pt/$\textit{n}$-SrTiO$_{3}$ heterostructures and
$\textit{n}$-SrTiO$_{3}$ thin films, respectively. The
surface contact of the heterojunction exhibit an increased
transport barrier after annealing in oxidizing conditions
while the thin films demonstrate a reduced carrier
concentration directly after growth in oxidizing conditions
and a $\textit{p}$O$_{2}$-dependent in-plane sheet
resistance.},
cin = {PGI-7},
cid = {I:(DE-Juel1)PGI-7-20110106},
pnm = {524 - Controlling Collective States (POF3-524)},
pid = {G:(DE-HGF)POF3-524},
typ = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
url = {https://juser.fz-juelich.de/record/872825},
}