Influence of moderate temperature annealing on surface fermi level in p-type InP: X-ray photoemission study

Influence of annealing on the surface band bending potential V/sub s/ in p-type (100) InP wafer has been investigated by X-ray photoelectron spectroscopy (XPS) as well as photoreflectance (PR). Our previous optical observation of the 220 /spl deg/C annealing-induced abrupt change in V/sub s/ was also observed by the present XPS study, although X-ray irradiation due to XPS affects strongly V/sub s/ of the sample annealed at temperatures below 200 /spl deg/C and above 300 /spl deg/C. In addition, it is shown that annealing at 220 /spl deg/C causes an abrupt change in the chemical shift of near surface In atoms. A phenomenological explanation for the mechanism of the Fermi level pinning at (100) InP surface will be proposed.