Kinetics of Oxidation on Differently Treated GaAs (100) Surfaces Studied by XPS and STM

Abstract

The kinetics of oxidation on (100) surfaces after different chemical treatments are studied by XPS and STM. Etching in an alkaline solution containing , photochemical etching and sulfur passivation in a solution are compared regarding oxidation, surface stability in air, and electrical homogeneity. In contrast to alkaline etching, photochemical etching delays oxidation, and sulfur passivation makes the surface resistant to a subsequent uptake of oxygen for at least 50h in air. STM images after photochemical treatment show larger inhomogeneities than after passivation, and changes in surface structures in air are recorded correlating with the degree of oxidation.