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@PHDTHESIS{Rupp:789051,
author = {Rupp, Jonathan Amadeus},
othercontributors = {Waser, Rainer and Lemme, Max C.},
title = {{S}ynthesis and resistive switching mechanisms of mott
insulators based on undoped and {C}r-doped vanadium oxide
thin films : as function of nanostructure and material
properties},
school = {Rheinisch-Westfälische Technische Hochschule Aachen},
type = {Dissertation},
address = {Aachen},
reportid = {RWTH-2020-04960},
pages = {1 Online-Ressource (IX, 305 Seiten) : Illustrationen,
Diagramme},
year = {2020},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University; Dissertation, Rheinisch-Westfälische Technische
Hochschule Aachen, 2020},
abstract = {The rapid evolution of electronics and their performance
progress in the past decades call for extremely fast,
scalable and power efficient memory technologies at the
lowest cost. The dominating contemporary memory types of
information technology (dynamic random access memory
“DRAM” and Flash) shortly approach their physical and
technological limits beyond which no further scaling is
neither possible nor economically feasible. Hence, there is
an urgent need for research of alternative memory and logic
concepts. One novel memory class consists of a very simple
two terminal device structure of an electrically active thin
film sandwiched between two electrodes. After its working
principle, it is called resistive switching random access
memory (“ReRAM” or “RRAM”). Stored information is
represented by the resistance of the electrically active
thin film which can be switched between at least two
distinguishable states. Macroscopically, resistive switching
is controlled by applying an appropriate electrical
potential to the device. Depending on the nanoscopic
switching mechanism, the device responds with a volatile or
a non-volatile change in resistance. In the past few years,
ReRAM technology increased in popularity due to its
promising device properties with excelling speed,
scalability, energy efficiency and endurance. Nowadays, it
is seen as one hot candidate to be able to compete both with
DRAM as well as Flash and could even open new fields of
computation towards neuromorphic circuits. In this thesis,
the potential of (and control over) resistive switching
mechanisms in undoped and chromium doped vanadium oxide thin
films is explored. The material class of vanadium oxides is
well known for its abundance of extraordinary electric and
magnetic properties such as the presence of electron
correlations and the formation of Mott-insulating states in
VO2 and Cr-doped V2O3. Therefore, three different synthesis
processes are established to determine the (crucial)
influence of defect density on electrical switching
properties. Low oxygen content thin films are reactively
sputtered at room temperature (I) which result in amorphous
undoped and Cr-doped VOx=1.5-2, at elevated temperatures
(II, > 673 K) for crystalline Cr-doped V2±ΔyO3 and at room
temperature with a post-reduction step (III), resulting in
Cr-doped V2O3 with excellent stoichiometry. The three
established synthesis processes generate largely different
morphological and electrical properties in the same type of
material. Moreover, resistive switching mechanisms and
kinetics of ReRAM devices are investigated in a large
temperature range between 80 K and 370 K. At least two
volatile and at least four non-volatile types of switching
mechanisms have been identified and have been classified
with respect to crystallinity, defect density, Cr-doping,
stack symmetry, device size and current compliance. Two
volatile switching types could be tracked back to mechanisms
such as crystallographic phase change in (Cr:)VO2 and a
thermal feedback event in Cr:V2O3. Four non-volatile
mechanisms may result as consequence of ionic drift, local
valence change (e.g. by oxygen vacancies), thermochemical
redox reactions and electron-electron correlations. Lastly,
the resistive switching performance of ultra-thin (10 nm)
Cr-doped V2O3 films is probed by local conducting atomic
force microscopy in ultra-high vacuum. A mix of volatile and
non-volatile characteristics can provide a multitude of
operation principles in the same device. Finally, strong
scaling potential below dimensions of less than 250 nm³
makes the material class attractive for selector as well as
memory applications.},
cin = {611610 / 618710},
ddc = {621.3},
cid = {$I:(DE-82)611610_20140620$ / $I:(DE-82)618710_20170609$},
pnm = {DFG project 167917811 - SFB 917: Resistiv schaltende
Chalkogenide für zukünftige Elektronikanwendungen:
Struktur, Kinetik und Bauelementskalierung "Nanoswitches"
(167917811)},
pid = {G:(GEPRIS)167917811},
typ = {PUB:(DE-HGF)11},
doi = {10.18154/RWTH-2020-04960},
url = {https://publications.rwth-aachen.de/record/789051},
}
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