X-ray photoelectron spectroscopy studies of Ag photodoping in Se-Ge amorphous films

The Ag-deposited Se80Ge20 (at. %) amorphous films are found to show a large chemical shift (∼1.2 eV) in the Se 3d level toward lower binding energies and to form a Ag2Se phase on the surface region. The chemical shift of the Se 3d level by Ag photodoping becomes large with increasing UV exposure (15 mW/cm2) and is saturated at about 0.6 eV for UV exposure of more than 60 s. The chemical shift can be almost explained by the electronegativity scale. Pauling’s charge on the Se atom can be estimated as −0.04 in the Ag-photodoped state.