AN XPS STUDY OF GAN THIN-FILMS ON GAAS

The energies of photoelectron and Auger lines of gallium and nitrogen in GaN thin films obtained by reactive sputtering are derived. From previous RBS investigations, such were found to be stoichiometric in the bulk. The XPS surface analysis of the films gives a chemical content of ∼20% gallium oxide. Depth profiling of GaN/GaAs samples is then performed by Ar+ (2 keV) sputter‐etching. The Ga L3M4,5M4,5 Auger line shows a partial dissociation of GaN by preferential sputtering of nitrogen and the production of metallic gallium. The Ga 3d and Ga 2p photoelectron lines, having different escape depths, give the same result. The etching rate is high: the GaN sputtering yield, which is almost the same as that for Ga, is found to be ∼8. The gallium oxide component disappears for depths larger than 10 nm: it is concluded that the surface gallium oxide is probably due to the partial oxidation of GaN films in atomospheric air. Copyright © 1990 John Wiley & Sons Ltd.