Defect processes in GaP: Implications for the behavior of excited surface defects

Abstract

We have investigated the different charge states and geometries of the P vacancy and Ga antisite defects in bulk GaP as well as on the GaP(110) surface. Similar behavior is observed for both the bulk and surface. The charged P vacancy VP+ exhibits symmetric outward relaxations from the vacancy site while VP0 and VP- display distortions that lower the symmetry. For the Ga antisite defect (GaP), the neutral GaP0 has a broken-bond configuration with one of its Ga nearest neighbors, while GaP- and GaP2- both have the centered configuration. However, due to their lack of symmetry, the atoms at the surface display a larger distortion. The effects of excitations initially lead to a more positive charge state of the surface defects and subsequently to bond weakening. © 1993 The American Physical Society.