Thickness-dependent metal-insulator transition in V2O3 ultrathin films

In this study, V2O3 ultrathin films about 5-20 nm thick were prepared on Al2O3 (0001) substrates through a reactive. evaporation process. Auger electron spectroscopy and x-ray photoelectron spectroscopy have been, used in situ to characterize their compositions and chemical states. Electric resistance measurements show that V2O3 films transform from metallic to semiconducting with the decrease of film thickness, which results from the a(1g) level rising because the lattice mismatch between the substrate and the film expands the c/a parameter ratio. No temperature-induced metal-insulator transition (Like that in bulk V2O3) was observed in V2O3 thin films at low temperature. We conclude that stress plays a major role in suppressing the temperature-induced metal-insulator transition. (C) 2004 American Institute of Physics.