Non-stoichiometric gallium oxide with cubic structure directly integrated to C-Cut sapphire

Abstract

We used oxygen-reactive electron beam evaporation and post-deposition thermal treatment to prepare thin films of gamma-phase gallium oxide (γ-Ga2O3) grown on c-cut sapphire substrates. Films were prepared at room temperature under different partial pressures of oxygen present (from 1.0 mPa to 8.0 mPa). After thermal treatments at 600.0 °C for 30 min, the films have different surface morphologies, which is evidences by atomic force microscopy. Scanning electron microscopy with energy dispersive spectroscopy analyses reveal the formation of non-stoichiometric Ga2O3 films, that uniform coat the substrates. X-ray diffraction analyses reveal the formation of γ-Ga2O3-x (0.4 < x < 0.6) with crystalline planes (001) preferably oriented parallel to the substrate surface but slightly tilted (less than ± 0.2°) in relation to the direction [001] of the c-cut sapphire substrates. Raman spectroscopy suggest that films despite structurally oriented present high degree of chemical disorder but with no evidence of other Ga2O3 polytypes formation. Such a simple route for the preparation of non-stoichiometric γ-Ga2O3 is promising for several catalytic applications and developments of light emitting devices.