Epitaxial lateral overgrowth of GaN over AlOx surface formed on Si substrate

An approach by which single crystal α-GaN can be grown laterally over oxidized AlAs $({\mathrm{AlO}}_x)$ formed on Si substrates is demonstrated. Regular $\mathrm{\alpha -}{\mathrm{Ga}}_{\mathrm{2}}{\mathrm{-O}}_{\mathrm{3}}$ stripe templates, spatially separated by ${\mathrm{AlO}}_x,$ on which subsequent GaN growth is selectively seeded are formed. Since the boundary between the stripe template and ${\mathrm{AlO}}_x$ is nominally planar, two pyramidal planes on separated GaN can merge by growing laterally over the ${\mathrm{AlO}}_x$ (referred to as planar epitaxial lateral overgrowth). Transmission electron microscopy reveals that the number of structural defects in GaN laterally grown over the ${\mathrm{AlO}}_x$ is remarkably reduced compared to that in GaN grown on the stripe templates, and accordingly cathodoluminescence reveals a strong band edge emission from GaN laterally grown over the ${\mathrm{AlO}}_x,$ suggesting that this approach allows us to grow GaN on Si substrates with fewer defects.