REACTIVE ION (N-2(+)) BEAM PRETREATMENT OF SAPPHIRE FOR GAN GROWTH

Efficiency and lifetime of GaN based light emitting diodes and laser d iodes can be improved by proper choice of substrate or deliberate modi fication of the substrate surface before deposition. Buffer growth or nitridation is the usual choices of surface modifications for GaN depo sition to improve crystal duality and optical properties. It was our i ntention to study a possibility that a reactive ion beam (RIB) pretrea tment of the sapphire substrate at room temperature could substitute t he nitridation process at high temperature above 1000 degrees C. The o ptical property of GaN films deposited on the sapphire surfaces pretre ated by the reactive ion beam has improved significantly. Current obse rvations clearly demonstrates that the RIB pretreatment of the sapphir e surface can be used to improve the GaN films grown by metalorganic c hemical vapor deposition (MOCVD). (C) 1998 Elsevier Science S.A. All r ights reserved.