ELECTRONIC AND ATOMIC-STRUCTURE OF 2-DIMENSIONAL ERSI2 (1X1)-H ON SI(111)

The electronic and atomic properties of H chemisorbed on the two-dimen sional (2D) ErSi2 (1 x 1) surface are studied using the extended Hucke l theory method. Calculated electronic density of states and 2D band s tructure of various H chemisorption geometries are compared with angle -resolved photoemission (ARP) data. From this comparison it is conclud ed that a geometry in which two H atoms are adsorbed per unit cell is the more consistent with the ARP data. They are bound respectively to the Si dangling bonds present at the ErSi2 surface and to Er in the in terstitial voids of the Er hexagonal plane below Si species of the out ermost atomic plane of the buckled Si top layer. We have also performe d an overlap populations analysis, which allows us to trace back the u nique buckling reversal of the Si top layer upon H saturation to an op timization of the Er-Si chemical bonding in H-saturated silicide.