Effects of Hydrogen Dilution of Silane on Properties of Glow-Discharged Undoped Hydrogenated Silicon

Abstract

The electrical and photoelectronic properties of glow-discharged hydrogenated silicon films were measured as a function of the hydrogen-dilution ratio of silane. At low silane fractions SiH₄/(SiH₄+H₂) below 10%, the formation of the so-called microcrystalline state was confirmed by X-ray diffraction analysis. However, the electron mobility measured by the time-to-flight method showed no drastic change after microcrystalline formation. The temperature dependence of the steady-state photoconductivity is quite different for samples in the amorphous (silane fraction > 10%) and microcrystalline (silane fraction < 10%) states, reflecting a difference in the recombination process. However, as far as the room-temperature photoconductivity is concerned, no great change is observed among samples deposited at different dilution ratios.