High-rate growth of stable a-Si:H

Correlation between the gas phase species in silane plasma measured by mass spectrometry and the properties of hydrogenated amorphous silicon (a-Si:H) films deposited by plasma enhanced chemical vapour deposition (PECVD) has been investigated. We have especially been interested in the higher-order silane related species in the plasma, whose contribution to the film growth is considered to be the cause of light-induced degradation in the film quality, especially at high growth rate. In this study, we varied excitation frequency, gas pressure and power density to vary the growth rates of a-Si:H films ranging from 2 Angstrom/s to 20 Angstrom/s. Molecular density ratio of trisilane, representative of higher silane related radicals, to monosilane has shown a clear correspondence to the fill factor after light soaking of Schottky cells fabricated on the resulting films.