Enhancement of epitaxial lateral overgrowth in the mist chemical vapor deposition of<i>α</i>-Ga₂O₃by using a-plane sapphire substrate

Abstract

Selective area growths of α-Ga2O3 were demonstrated on c-, m-, and a-plane sapphire substrates by the mist-CVD method using SiO2 as a mask material. We successfully achieved the coalescence of the α-Ga2O3 on the mask with the stripe on an a-plane sapphire substrate by epitaxial lateral overgrowths, owing to the enhanced lateral overgrowth, that is, the largest ratio of the lateral to vertical growth rates of 0.87 among the substrate orientation and the stripe direction investigated. In cross-sectional transmission electron microscopy images, dislocations were not observed in the α-Ga2O3 layer on the mask, while the dislocations on the window area were propagated without bending.