Preconditioning of c-plane sapphire for GaN molecular beam epitaxy by electron cyclotron resonance plasma nitridation

Nitridation of c-plane sapphire is often used in molecular beam epitaxy of GaN to improve crystalline quality in deposited layers. X-ray photoelectron spectroscopy, reflection high and low energy electron diffraction, Auger sputter profiling and atomic force microscopy, were used to investigated the chemical and structural properties of sapphire (0001) substrate on exposure to nitrogen. A monolayer of surface nitride formed after around 60 minutes of nitridation.