Nonpolar a-plane GaN grown on r-plane sapphire using multilayer AlN buffer by metalorganic chemical vapor deposition

▶ Mirror-like and pit-free non-polar a-plane (1 1 −2 0) GaN films are grown on r-plane (1 −1 0 2) sapphire substrates using metalorganic chemical vapor deposition (MOCVD) with multilayer high-low-high temperature AlN buffer layers. The multilayer AlN buffer structure includes a thin low-temperature-deposited AlN layer inserted into the high-temperature-deposited AlN layer. The results demonstrate that the multilayer AlN buffer structure can improve the surface morphology of the upper a-plane GaN film.