Oxide states spectroscopy of real Ge surfaces

The electronic structure of surface oxide has been investigated by measurements of internal photoemission and photoconductivity measurements for p-type single crystalline Ge specimens with real surfaces. The photo-response curves show bulk and surface effects which are separated by differential methods. Emission from the bulk into oxide states or from oxide states into the bulk result in positive or negative changes of surface conductivity. The oxide states are distributed in energy with maxima near the conduction-band edge and the valence-band edge of the oxide. Changes of the electronic structure are observed by X-irradiation and storage in laboratory air.