Preparation of GaN film of low carrier density by the HWE system with Ga and TMG sources

GaN films with low carrier density of the order of 1016cm−3, smooth and mirror like surface morphology, and good crystalline quality were prepared on a (0001)sapphire substrate by the hot wall epitaxy system using Ga metal and TMG gas source, respectively. To investigate the dependence of the quality on the thickness of the GaN buffer layer, several ramping rates were performed between the growth of the buffer and the epi-layer. A simple model is proposed to explain the results.