Phase-controlled epitaxial lateral overgrowth of α-Ga2O3 by halide vapor phase epitaxy

Abstract

We investigated the effect of mask materials on the epitaxial lateral overgrowth (ELO) characteristics of α-Ga2O3 and developed an ELO technique that can markedly suppress abnormal growth and cracking to enable long-term growth on a wide mask, which is necessary to effectively improve the crystal quality. A conventional SiOx mask provided excellent growth selectivity with only a thin amorphous GaOx layer on the mask between α-Ga2O3 islands. However, the amorphous layer transformed into β-Ga2O3, which disrupted the long-term growth of α-Ga2O3. Amorphous deposition was avoided by using a TiOx mask. When a TiOx mask was used, κ-Ga2O3 deposited on the mask, and no transformation to β-Ga2O3 was observed. α-Ga2O3 islands with a diameter as large as approximately 25 μm were grown by the developed ELO technique using a TiOx mask. Transmission electron microscopy observation did not detect dislocations in the outermost part of the islands.