Initial growth of GaN on sapphire(0 0 0 1) using an amorphous buffer layer formed at room temperature by RF-MBE

Abstract

The two-step growth process of GaN layer on sapphire using a buffer layer deposited at room temperature has been investigated by in situ reflection high-energy electron diffraction and atomic force microscopy observations. A stepped and (9×9) reconstructed surface structures are formed on the sapphire substrates annealed at 900°C before deposition of the GaN buffer layer. It is found that no nitridation of the sapphire surface occurred under radio frequency plasma-enhanced nitrogen gas irradiation at 900°C for 10min. It has been found that the amorphous GaN buffer layer deposited at room temperature changes to the single crystal by annealing at 700°C. It is concluded that the GaN epilayer with the flat surface is successfully grown on sapphire(0001) by using the amorphous GaN buffer layer.