Epitaxial growth of V2O3 thin films on Si(111) by molecular beam epitaxy

Vanadium sesquioxide (V2O3) is a strongly correlated electron material exhibiting two distinct metal-insulator transitions that can be tuned via strain, doping, or pressure, making it an interesting material for new-generation sensors or smart devices. For this purpose, it is required to achieve well-ordered epitaxial thin film growth with high-quality electrical and optical properties on technologically relevant substrates. We report the successful growth of epitaxial thin films of V2O3 via molecular beam epitaxy, in the paramagnetic insulating (PI) phase on the (1 1 1) plane of silicon, by tailoring the growth conditions. Extensive electrical, structural, and morphological characterization both in situ and ex situ has been performed on all samples. The structural analysis reveals that temperature plays a more impactful role in affecting the thin film microstructures than the oxygen partial pressure. When the epitaxy of V2O3 occurs on the unoxidized (1 1 1) plane of silicon, four equivalent epitaxial domains begin to form, leading to twin boundaries in the bulk of the film. The considerable lattice mismatch between silicon and V2O3 induces the growth of the corundum PI phase. Lastly, small deviations from stoichi-ometry due to different oxygen inflow during growth alter significantly the resistivity change upon cooling.