Bulg. J. Phys. vol.25 no.1-2 (1998), pp. 081-085

Relation Between the Properties of a-Si:H Thin Films and the Growth Rate

A. Toneva, Tz. Mihailova
Central Laboratory of Solar Energy and New Energy Sources, 72 Tzarigradsko Chaussee Blvd, 1784 Sofia
Abstract. The results following an extensive characterization study involving dark- and photoconductivity measurements as a function of temperature, and the optical and structural properties of hydrogenated amorphous silicon (a-Si:H) thin films prepared at varying deposition rates were analyzed. The thin films were deposited by homogeneous chemical vapour deposition at low pressure. The growth rates were varied by changing the gas pressure and gas temperature. We found that the activation energy, the conductivity pre-exponential factor, the photo-sensitivity, the refractive index and the inhomogeneity parameter exhibit a maximum in the dependence on the deposition rate. The optical band gap and the optical coefficient B, including information on the band tail states, do not change significantly with the increase of the deposition rate.

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