CHEMICAL-VAPOR-DEPOSITION OF AMORPHOUS-SILICON USING TETRASILANE

Hydrogenated amorphous-silicon films have been deposited by the plasma-free chemical-vapor-deposition method using tetrasilane (Si4H10) at temperatures as low as 350-degrees-C. The film deposited at 350-degrees-C and 9 Torr had hydrogen content as high as 15 at. %, optical bandgap of 1.78 eV, logarithmic ratio of photoconductivity (at a light intensity of 100 mW/cm2 under AM1 conditions) to dark conductivity of 3.2, activation energy of 0.78 eV and the Urbach tail slope as small as 56 meV. Thin-film transistors have been fabricated using the film deposited at 350-degrees-C. The electron mobility was 0.6 cm2/V s under as-deposited conditions.