PLASMA-ENHANCED CHEMICAL VAPOR-DEPOSITION OF AMORPHOUS-SILICON SELENIUM ALLOY-FILMS

Amorphous silicon-selenium alloys were prepared by plasma-enhanced chemical vapor deposition. It was found that the Si-Se alloy is a wide band-gap semiconductor. The optical band-gap of the alloy changed from 1.7 to 2.0 eV, as a function of the selenium concentration in the film. The light to dark conductivity ratio was of the order of 1.5 x 10(3). The dangling bond density was estimated from electron spin resonance measurements, and the elemental content and distribution were analyzed by the secondary ion mass spectrometry, energy dispersive X-ray spectroscopy and electron probe micro analysis techniques. The results show that the amorphous silicon selenium alloy is a promising material for multi-band-gap photovoltaic devices.