Epitaxial growth of α-Ga2O3 thin films on a-, m-, and r-plane sapphire substrates by mist chemical vapor deposition using α-Fe2O3 buffer layers

Epitaxial a-, m-, and r-plane alpha-Ga2O3 thin films were successfully grown on a-, m-, and r-plane sapphire substrates through the insertion of alpha-Fe2O3 buffer layers using mist chemical vapor deposition. The alpha-Fe2O3 buffer layers improved the crystal growth of the alpha-Ga2O3 thin films. We reveal that the out-ofplane and in-plane orientations of each plane alpha-Ga2O3 thin film corresponded to that of each plane sapphire substrate. The direct bandgap of the alpha-Ga2O3 thin films from the optical transmittance and reflectance results of a-, m-, and r-planes was estimated to be 5.15-5.2 eV. The epitaxial alpha-Ga2O3 thin films on the various sapphire substrates are promising materials for power devices and deep ultraviolet region optoelectronic devices. (C) 2017 Elsevier B.V. All rights reserved.