Morphological anisotropy and mosaicity in epitaxially grown VO2 films
Epitaxially grown films of VO2 are one of the most promising materials for oxide electronics due to a very convenient temperature and remarkable controllability of the insulator-to-metal phase transition (IMT) by doping, strain, photo excitations or applying an electric field. Scaling the IMT-based devices down to submicron size is a technological challenge because of the high variability of the resulted functional characteristics from device to device. Our work focuses on the structural and morphological origins of such variations. We used X-ray nano diffraction mapping to study the evolution of mosaicity, strain and phase coexistence in 70 nm thick VO2 film (r-cut Al2O3) during thermal cycling and annealing. We found high anisotropy in the grain and crack network structure which remarkably resonates with anisotropy of transport properties. We were able to distinguish a persistent morphological pattern due to the film manufacturing from transient features introduced by thermal cycling. Our results manifest the important role of nanomorphology in the performance of VO2-based nanodevices. We suggest that it can also be considered as a new degree of freedom to control functional properties in oxide electronics.This work was supported by DOE- Office of Basic Energy Sciences.
APS March Meeting Abstracts
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