Direct growth of flexible GaN film via van der Waals epitaxy on mica

Abstract

A flexible gallium nitride (GaN) thin film was obtained on fluorphlogopite-mica through van der Waals epitaxy using an optimized two-step growing process in a hydride vapor phase epitaxy system. The interfacial stress caused by the mismatches of thermal expansion coefficient was significantly reduced via van der Waals epitaxy. The proposed two-step growth allows such low-stressed GaN thin film forms on mica directly where a critical (minimum) growth pressure was defined and the temperatures chosen were optimized. The transmittance was controlled by surface roughness and growth temperature, as high density of defects near their interface caused by GaN decomposition leading the GaN film non-transparent. In the measurement region, the average transmittance decreased linearly as the GaN surface became rougher. The bending of the flexible GaN thin film caused only slight PL peak shift. Thus, such direct grown GaN film on fluorphlogopite-mica can be evaluated as a reliable optical device.