XPS and LEISS studies of ion bombarded GaSb, InSb and CdSe surfaces

Abstract

Ion bombardment effects in GaSb, InSb and CdSe crystal surfaces were studied with a combination of X-ray photoelectron spectroscopy (XPS) and low energy ion scattering spectroscopy (LEISS). Both XPS and LEISS showed that neglecting surface contamination, the composition of the crystal surfaces prior to ion bombardment were close to their stoichiometric values of 1:1. During 3 keV Ar + beam bombardment, XPS analysis showed that the atomic ratios of Sb Ga , Sb In and Se Cd in the bombarded surfaces decreased from 1 to 0.71, 0.92 and 0.87, respectively. LEISS results, indicated that these ratios increased to 3.33, 1.63 and 1.32, respectively. The variances between XPS and LEISS measurements are attributed to a difference in the sampling depth between the two techniques, and give a clear indication of how ion bombardment changes the surface composition of these compound semiconductors. These changes may be described in terms of bombardment-induced Gibbsian segregation.