Occupation of Surface States and Surface Band-Bending in Thermal Equilibrium

Abstract

Surface states at semiconductor surfaces exhibit donor or acceptor character. Depending on their position with respect to the Fermi level they are neutral or become charged either positively or negatively, respectively. A charging of surface states necessarily results in the formation of a space-charge layer beneath the surface and, in thermal equilibrium, the surface band-bending adjusts such as to satisfy the condition of surface charge neutrality.