Strong surface Fermi level pinning and surface state density in GaAs_(0.65)Sb_(0.35) surface intrinsic-n~+ structure

摘要

Room-temperature photoreflectance is employed to investigate the Fermi level pinning and surface state density of a GaAs_(0.65)Sb_(0.35) surface intrinsic-n~+ (SIN~+) structure. Based on the thermionic emission theory and current-transport theory, the surface Fermi level V_F and surface state density are determined experimentally from the dependence of the surface barrier height on the pump beam intensity. The surface state density D_s is estimated as approximately 1.91 × 10~(13) cm~(-2), and the Fermi level is located G.63 eV below the conduction band edge at the surface. By sequential etching of the intrinsic layer, the Fermi level pinning in GaAs_(0.65)Sb_(0.35)SIN~+ structure is further demonstrated.