Epitaxial lateral overgrowth of ε-Ga2O3 by metal–organic chemical vapor deposition

Orthorhombic ε-Ga2O3 is the second most stable phase of the Ga2O3 family, which is usually grown on hexagonal substrates by hetero-epitaxy. Due to the mismatch of rotational symmetry between the ε-Ga2O3 film and the substrate, the hetero-epitaxy of ε-Ga2O3 is accompanied by the problem of rotation domains, which brings a high density of defects in the film. This paper focuses on the epitaxial lateral overgrowth (ELO) of ε-Ga2O3 by metal–organic chemical vapor deposition (MOCVD). Based on the investigation of nucleation temperature, mask period and direction, the optimal conditions for the ELO growth of ε-Ga2O3 via MOCVD are established. It is found that both the thermal diffusion capability of Ga adatoms and the growth rate anisotropy of ε-Ga2O3 play important roles during the ELO of ε-Ga2O3. A high growth temperature and a short mask period can suppress the nucleation of irregular ε-Ga2O3 grains and improve the crystal quality. Further comparison of different designs of ELO masks revealed that the striped ELO masks predominantly promote the quasi-single-domain growth of ε-Ga2O3. Notably, for samples with striped ELO windows along the sapphire $$\left\langle {11\overline{2}0} \right\rangle$$ , rotation domains are effectively suppressed and the ratio of 0°, + 120°, and − 120° domains increases from 1.01:1:1 to 2.6:1:1.