Photoemission study of nitrogen-implanted GaAs surfaces

Monocrystalline p- and n-type GaAs (100) substrates were bombarded with 3-keV Ar+ and 10-keV N+ ions. Chemical states and composition of the surface were analyzed from x-ray and uv photoemission spectroscopy with photoelectron escape depths of 5–20 Å. Ion sputter etching eliminates chemisorbed impurities and produces an As deficit near the surface involving a high reactivity. For nitrogen-ion implantation, N atoms partially substitute to As atoms, which gives an unsaturated GaAs1−x Ny compound in our experimental conditions. The analysis with the He ii line (ℏω=40.8 eV) shows predominance to GaN close to the surface.