Field-effect conductance change in amorphous silicon

The change in conductance of an amorphous silicon film due to a transverse electric field was observed. The films were electron-beam vacuum deposited at controlled rates of less than 5 Å/sec onto Si–SiO2 substrates and then annealed for 4 h at 400 °C. The results indicate that the Fermi level is not pinned at near midgap and that the localized states are nearly uniform over a 0.4-eV section above and 0.4 eV below the Fermi level near the middle of the energy gap. Calculations show the density of localized states to be 1020/eV cm3 over this region and to be reduced as the deposition rate decreases.