Effects of hydrogen contamination on the localized states in amorphous silicon

The effects of incorporating hydrogen into vacuum-evaporated amorphous silicon films as measured by the field-effect conductance change is reported. Analysis of the data indicates that the density of localized states near the Fermi level decreases from 1×1020/cm3 eV to 2.8×1019/cm3 eV as the partial pressure of hydrogen during vacuum evaporation is increased from 7×10−6 to 6×10−5 Torr, with all other sample preparation procedures fixed. Under the same conditions the resistivity increases as the partial pressure of hydrogen is increased.