The localized density of states in amorphous silicon determined by electrophotography

Abstract

The localized density of states g(E) near midgap for undoped, B2H6-doped, and PH3-doped hydrogenated amorphous silicon is evaluated from the electrophotographic (xerographic) method. The density of hole traps decreases with increasing B2H6 concentration and that of electron traps decreases with increasing PH3. These features are qualitatively similar to those deduced from the deep-level transient spectroscopy, the photothermal deflection spectroscopy, the time-of-flight measurements, and the isothermal capacitance transient spectroscopy. The energy positions of neutral dangling bonds D0 and doubly occupied D− are estimated to be 0.85–0.88 eV from the valence band and 0.62–0.67 eV from the conduction band, respectively. Comparison of the energy peaks of electron and hole traps shows that the positive correlation energy of dangling bonds is about 0.3–0.4 eV.