Influence of post-annealing on properties of $alpha$ -Ga 2 O 3 epilayer grown by halide vapor phase epitaxy

Effect of annealing to realize high-quality $\alpha$ -Ga 2 O 3 epilayers grown by halide vapor phase epitaxy has been studied. The structural and optical properties of $\alpha$ -Ga 2 O 3 changed with changing annealing duration. In particular, for an annealing duration of 3 min, the crystal quality improved from 51 and 2757 arcsec to 28 and 1539 arcsec for (0006) and (10-14) FWHM, respectively. X-ray photoelectron spectroscopy results confirmed that the oxygen gas during annealing reacted to compensate the oxygen vacancies in the $\alpha$ -Ga 2 O 3 epilayers. These results show that the optimized thermal annealing improved the crystal quality of $\alpha$ -Ga 2 O 3 epilayers.