Isothermal Photocurrent Transient Spectroscopy of Gap States in Amorphous Chalcogenide Semiconductors

Abstract
Gap state spectroscopy for determining the density and distribution of gap states in amorphous chalcogenide semiconductors is described. The method is based on the analysis of the transient current after a light pulse. The applicability of the method for determining the gap states in a-Se:Te films has been experimentally demonstrated. The experiments reveal that the gap states are relatively discrete states at energies of 0.42 eV and 0.34 eV above the valence band edge for 12 at.% Te:Se films and 18 at.% Te:Se films respectively.