BAND BENDING AND FERMI LEVEL SHIFTS IN PHOSPHORUS-DOPED HYDROGENATED AMORPHOUS-SILICON STUDIED BY X-RAY PHOTOELECTRON-SPECTROSCOPY

X-ray photoelectron spectroscopy (XPS) was used to explore the surface of phosphorus-doped hydrogenated amorphous silicon, a-Si: P,H. P was found to exist in two forms: as P incorporated into the Si matrix and as surface-segregated, oxidized P. Silicon core levels were shown to manifest Fermi level shifts. Angle-resolved XPS was used to show the circumstances under which band bending occurred. For the first time, digital filtering was used to remove the noise from the XPS signal in the Si 2p plasmon-P 2p multiplet region near 130 eV, permitting their separation.