SURFACE ATOMIC-STRUCTURE OF INAS((111)OVER-BAR)2X2 AND INSB((111)OVER-BAR)2X2 STUDIED BY CORE-LEVEL SPECTROSCOPY

Surface sensitive high resolution core level spectroscopy has been app lied to the molecular beam epitaxy grown InAs((111) over bar)2 x 2 and InSb((111) over bar)2 x 2 surfaces. For both systems the In 4d core l evel consists of one dominating component while the Group V core level s are deconvoluted into four components. This analysis is consistent w ith a surface model where the topmost layer consists entirely of arsen ic or antimony. In this model, Group V atoms form trimers bound to Gro up V atoms in the first double layer, leaving a single Group V rest at om per unit cell.