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

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

Automated summary

A significant anisotropy in electrical conductance was observed in Si-doped alpha-Ga2O3/sapphire samples grown via liquid-injection metal organic chemical vapor deposition. X-ray diffraction (XRD) revealed the presence of (010) beta-Ga2O3 in addition to epitaxial alpha-Ga2O3. Various characterization techniques confirmed the formation of (010) beta-Ga2O3 filaments in undoped alpha-Ga2O3 film. Conductive AFM and current-voltage measurements confirmed the higher conductivity along the [2(1)(1)0] alpha-Ga2O3 direction compared to [0001] alpha-Ga2O3 direction, attributed to the presence of beta-Ga2O3 filaments.