Growth of α- and β-Ga2O3 epitaxial layers on sapphire substrates using liquid-injection MOCVD

Abstract

Ga2O3, a wide-bandgap semiconductor material, offers a great potential for power and high-voltage electronic devices. We report on the growth of undoped α- and β-phase Ga2O3 using liquid-injection metal-organic chemical vapor deposition (LI-MOCVD) on sapphire substrates. Using the same precursor (gallium acetylacetonate) and deposition temperature of 700 °C, the phase selection was controlled by the sapphire substrate orientation, where the growth of α- and β-phase Ga2O3 was achieved on m- and c-plane surface, respectively. As deduced from x-ray diffraction, α-Ga2O3 films show epitaxial character, while β- Ga2O3 films exhibit highly textured structure. Oxygen flow was also found to have a strong impact on the phase purity of α-Ga2O3 for the flow rates examined. Optical and electrical properties of the layers grown at different oxygen flow rates were also studied systematically. LI-MOCVD growth of α-phase Ga2O3 layers at relatively high deposition temperature widens the high-temperature processing of the Ga2O3-based electronic and optoelectronic devices.