Structural and optical properties of nonpolar (1 1 -2 0) a-plane GaN grown on (1 -1 0 2) r-plane sapphire substrate by plasma-assisted molecular beam epitaxy

Highlights: → Structural and optical study of a-plane GaN film grown on r-sapphire by PAMBE. → HRXRD was used to determine the epitaxial relation of a-plane GaN with r-sapphire. → The plane-view TEM reveals the formation of basal stacking faults in a-plane GaN. → Low temperature PL emission was found to be dominated by basal stacking faults. → Raman spectroscopy study shows that a-GaN film is compressively strained. -- We report the structural and optical properties of a-plane GaN film grown on r-plane sapphire substrate by plasma-assisted molecular beam epitaxy. High resolution X-ray diffraction was used to determine the out-of-plane and in-plane epitaxial relation of a-plane GaN to r-plane sapphire. Low-temperature photoluminescence emission was found to be dominated by basal stacking faults along with near-band emission. Raman spectroscopy shows that the a-GaN film is of reasonably good quality and compressively strained.