Electronic properties of both Pb and S vacancy defects in PbS(¯100) were studied using first-principles density functional theory calculations with plane-wave pseudopotentials. It was found that the density of states near to the top of the valence band and the bottom of the conduction band was significantly modified by these defects. The calculations indicated that, in the case of S vacancy defects, the Fermi energy shifted to the conduction band; making it an n-type PbS (donor). However, in the case of the Pb vacancy, because of the appreciable change in the density of states, the system acted as a p-type PbS (accepter). In addition, the structural relaxation showed that the defect led to outward relaxation of the nearest-neighbour atoms and inward relaxation of the next-nearest neighbour atoms.

First-Principles Study of Electronic Properties in PbS(¯100) with Vacancy Defect. Z.Ding, H.Z.Xing, S.L.Xu, Y.Huang, X.S.Chen: Chinese Physics Letters, 2007, 24, 3218-21