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Naturally formed ultrathin V2O5 heteroepitaxial layer on VO2/sapphire(001) film

Authors :
Guru Subramanyam
Gwo-Ching Wang
Kevin D. Leedy
Vladimir Vasilyev
KuanChang Pan
Zonghuan Lu
Tony Quach
Toh-Ming Lu
Aaron J. Littlejohn
Eunsung Shin
Y. B. Yang
Source :
Applied Surface Science. 419:365-372
Publication Year :
2017
Publisher :
Elsevier BV, 2017.

Abstract

Vanadium dioxide (VO2) and vanadium pentoxide (V2O5) thin films change their properties in response to external stimuli such as photons, temperature, electric field and magnetic field and have applications in electronics, optical devices, and sensors. Due to the multiple valence states of V and non-stoichiometry in thin films, it is challenging to grow epitaxial, single-phase V-oxide on a substrate, or a heterostructure of two epitaxial V-oxides. We report the formation of a heterostructure consisting of a few nm thick ultrathin V2O5 epitaxial layer on pulsed laser deposited tens of nm thick epitaxial VO2 thin films grown on single crystal Al2O3(001) substrates without post annealing of the VO2 film. The simultaneous observation of the ultrathin epitaxial V2O5 layer and VO2 epitaxial film is only possible by our unique reflection high energy electron diffraction pole figure analysis. The out-of-plane and in-plane epitaxial relationships are V2O5[100]||VO2[010]||Al2O3[001] and V2O5[03 2 ¯ ]||VO2[100]||Al2O3[1 1 ¯ 0], respectively. The existence of the V2O5 layer on the surface of the VO2 film is also supported by X-ray photoelectron spectroscopy and Raman spectroscopy.

Details

ISSN :
01694332
Volume :
419
Database :
OpenAIRE
Journal :
Applied Surface Science
Accession number :
edsair.doi...........bfd0e2baa81d61fdf65af71fda9e3689