Adsorption processes of Se on the GaAs(111)A-(2x2) surface

The adsorption processes of Se on the GaAs(111)A surface have been systematically studied using reflection high-energy electron diffraction (RHEED), scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and total-reflection-angle X-ray spectroscopy (TRAXS). We have found that a reconstructed structure of (2 root 3 x 2 root 3)-R30 degrees is formed on the Se-adsorbed GaAs(111)A. A structure model has been proposed for the GaAs(111)A-(2 root 3 x 2 root 3)-R30-Se surface, which consists of two Se trimers located at a hollow site of the GaAs(111)A surface and three Ga vacancies per unit cell. The proposed structure model sufficiently explains experimental data from RHEED, XPS, and STM, and satisfies electron counting requirements. (C) 2000 Elsevier Science B.V. All rights reserved.