On the Uniformity of Thin a-Si:H Films Prepared in an RF-Glow Discharge System

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Abstract
The present work reports a study of the uniformity of 500- to 4000-nm-thick a-Si:H films deposited by glow discharge from undiluted pure monosilane. The techniques chosen to study the uniformity of these films encompassed the obtaining of reflection interference patterns and transmission spectra (400 nm\leqslantλ\leqslant900 nm) of the film-substrate configuration. The film thickness d, the homogeneity parameter Δd and the optical properties such as n(λ), α(λ) and E 0 were calculated from the transmission data. Five preparation parameters, pressure, rf power, gas flow rate, substrate temperature and geometry of the anode were varied. The influence of a sixth parameter, film thickness, was also studied. The results showed that large variations occurred in the film thickness from point to point on a single film. In contrast to this, the other optical parameters n(λ), α(λ) and E 0 remained constant.