VISIBLE PHOTOLUMINESCENCE IN HIGHLY PHOTOCONDUCTIVE HYDROGENATED AMORPHOUS-SILICON DEPOSITED BY GLOW-DISCHARGE OF SIH4 HIGHLY DILUTED WITH HE

A wide-band-gap (>2.0 eV) hydrogenated amorphous silicon (a-Si:H) film showing visible photoluminescence (PL) is obtained by rf glow-discharge decomposition of SiH4 highly diluted with He. The PL and the structural properties of the a-Si:H are investigated. The He dilution leads to the extension of the band gap and the increase of the SiH2 and (SiH2)(n) configurations in the film. The PL increases rapidly and blue-shifts consistently with the increase of the SiH2 and (SiH2)(n) configurations. By observation using transmission electron microscopy and Raman scattering, it is found that the film consists of uniform amorphous structure and includes no microcrystallites. The him exhibits a photoconductivity (under AM-1 light of 100 mW/cm(2)) to dark conductivity ratio of over 10(6) in addition to a visible PL at room temperature. This new a-Si:H film has potential for application to an optical device with characteristics of both light emission and photosensitivity.