Abstract
Hydrogenated amorphous silicon films are deposited by a direct vacuum ultraviolet photochemical vapor deposition method. The light source is a microwave-excited Xe resonance lamp (wavelength=147nm). Undoped films are deposited using Si2H6 at substrate temperatures T sub of 200 – 400°C. Photo- and dark conductivity ratio of the films is as high as 105 under AM1(100mW cm−2) illumination for all the T sub. The film deposited at 300°C shows low photoconductivity degradation of 10% after 3-hour illumination and a low defect density of 2.2 × 1015cm−3. Doped films are deposited by the addition of PH3 for n-type and B2H6 for p-type at T sub of 250°C. Dark conductivity is controlled from 10−11 to 10−3S cm−1. The phosphorus doped films in particular show much higher photoconductivity than the dark conductivity. This is explained by the increase in ηµτ by the shift of Fermi level to the conduction-band side. Besides, relatively low defect density is suggested to bring about the additional increase in ηµτ.
Published Version
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