Conductance anisotropy of MOCVD-grown α-Ga2O3 films caused by (010) β-Ga2O3 filament-shaped inclusions

Abstract

Abstract A significant anisotropy in the electrical conductance was observed in Si-doped α-Ga2O3/sapphire samples grown via liquid-injection metal organic chemical vapor deposition. Additionally to epitaxial α-Ga2O3 diffraction, x-ray diffraction (XRD) revealed maxima related to (010) β-Ga2O3. Transmission electron microscopy, atomic force microscopy (AFM), and Raman spectroscopy of undoped samples with similar XRD pattern confirmed the formation of (010) β-Ga2O3 filaments in the epitaxial α-Ga2O3 film. In Si-doped samples, conductive AFM and temperature-dependent current–voltage measurement on transmission line measurement resistors confirmed, that β-Ga2O3 filaments were responsible for significantly higher conductivity along the 2 1 ˉ 1 ˉ 0   α-Ga2O3 direction compared to [0001] α-Ga2O3 direction. Current–voltage measurements of transistor structures suggested semiconducting behavior of the β-Ga2O3 filaments embedded in the highly resistive α-Ga2O3 films.