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 2ʹ3 =2ʹ3.–R308 is formed on the Se-adsorbed GaAs 111.A. A structure model has been proposed for the GaAs 111.A– 2ʹ3 =2ʹ3.–R308–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. q2000 Elsevier Science B.V. All rights reserved