Twin-induced phase transition from β-Ga2O3 to α-Ga2O3 in Ga2O3 thin films

We deposited a 300-nm-thick Ga2O3 thin film on an amorphous SiO2/Si substrate via pulsed laser deposition. X-ray diffraction patterns revealed the formation of beta-Ga2O3 phase at a substrate temperature of 700 degrees C. X-ray photoelectron spectra indicated that the degree of oxidation increased after annealing at 700 degrees C. Further annealings at higher temperatures led to a transition of the beta-Ga2O3 phase to the alpha-Ga2O3 phase; this transition was caused by the twin structure formed during the crystallinity improvement process. In addition, we discuss the mechanism of the transition from the beta phase to the alpha phase in the beta-Ga2O3 thin films. (C) 2018 The Japan Society of Applied Physics.