XPS study of the surface Fermi level of (NH4)2Sx-passivated GaAs(100) surface

In this paper we present the results of systematic XPS study of the surface Fermi-level postion at the sulfide-passivated GaAs(1 0 0) surface starting from the epi-ready sample through the different procedures of its dipping in a saturated polysulfide (NH4)(2)S-x solution, and finally combined with a UHV annealing. Moreover, the MBE As-stabilized GaAs(1 0 0) (2 x 4) surface was used as a reference sample. The surface Fermi level position in the band gap E-F - E-v after each processing step was determined from the position of the bulk component of binding energy of Ga3d and As3d core level spectra. Moreover, a correlation between the variation of electronic properties and surface chemistry of the GaAs(1 0 0) surface after sulfidation was derived from the analysis of the relative intensity of the main oxygen, carbon and sulfur XPS peaks. (C) 2002 Elsevier Science Ltd. All rights reserved.