NATURE OF NATIVE-OXIDE ON GAN SURFACE AND ITS REACTION WITH AL

In this letter, we describe the surface properties of GaN thin films g rown on sapphire substrate by molecular beam epitaxy, as revealed by u ltraviolet and x-ray photoelectron spectroscopic and Auger electron sp ectroscopic studies. The samples are seen to contain overlayer of nati ve oxides, which are predominantly in the Ga2O3 form. Ammonia is shown to be a good etchant for these native oxides. Furthermore, we investi gated the early stages of the reaction of monolayer Al with a GaN surf ace covered with native oxide, Aluminum reacts preferentially with the surface oxygen and leads to the formation of a mixture of oxides at t he interface. (C) 1996 American institute of Physics.