Surface structure of (NH4)2Sx-treated GaAs (100) in an atomic resolution

Abstract

The three‐dimensional structure of a GaAs (100) surface, treated in a (NH₄)₂S_x solution and annealed at 200 °C, was studied in an atomic scale by x‐ray photoemission spectroscopy (XPS), high‐resolution Rutherford backscattering spectroscopy (RBS), and scanning tunneling microscopy (STM). XPS spectra showed that S termination could suppress oxidization of the surface in the air and that S atoms on a GaAs surface bonded As atoms. The disorder of atomic sites in the surface region of a S‐terminated GaAs was found by RBS channeling spectra to be smaller than that of an untreated sample. The thickness of the sulfur layer on GaAs was found to be about 1.5 monolayers from RBS measurement. STM observation of the S‐terminated surface revealed a 1×1 lateral structure of the sulfur layer on the GaAs (100) surface.