Radio frequency plasma nitridation of c-plane sapphire; influence on properties of GaN grown by molecular beam epitaxy

The influence of radio frequency plasma nitridation and other pretreatments of c-plane sapphire on the surface morphology and electrical, optical properties of GaN layers grown on this substrate by molecular beam epitaxy (MBE), was examined with room temperature Hall mobility, low temperature photoluminescence, and scanning electron microscopy. The measurements show no clear difference in quality between GaN films deposited on pretreated and non-pretreated substrates. Ga-rich growth conditions appears to be the essential requirement for deposition of high-quality GaN layers by MBE.