The Fermi level position in doped amorphous silicon

Abstract

The shift of the Fermi energy with substitutional doping has been determined for glow-discharge amorphous silicon films by photoelectron spectroscopy. The values so obtained for n- and p-type specimens are in good agreement with the shift expected from the activation energy of the electrical conductivity and confirm that the Fermi level can be moved throughout most of the mobility gap of amorphous silicon. The data also show that the surface-state density at the Si-SiO2 interface is extremely low, so that information from field-effect experiments should be representative of the bulk states.