| As an important electronic material in energy-information industry, poly-silicon thin films are widely used in LSI and semiconductor discrete devices because of its excellent photoelectric characteristics and low-cost of preparation. Poly-silicon thin film solar cells with high efficiency, stability and low-cost would replace the a-Si thin film solar cells as a new generation of non-pollution civil solar cells. In order to low down its cost, many technologies have been developed to prepare the poly-silicon thin film in low temperature. However, each technology has some unfavorable factors for industrialized manufacture processes. PECVD is the most effective way for mass-production in that the films it prepared have high quality, the technique it used is mature, and the conventional PECVD system itself is quite fit for mass-production. SiCL1 is similar to SiF4 in structure and property, and it is a cheaper, safer raw material in industry to low down the cost of the productions more effectively in comparison with SiLl4 and SiF4. Based on the above, we attempt to deposit the poly-silicon films directly, using SiC14/H2, in conventional radio frequency glow discharge PECVD system, on the glass and the silicon substrates respectively, in order to find out the process technique for mass-production. We discover that poly-silicon thin films can be gained when the substrate temperature is 200 0C, which has not been reported yet at home and abroad. The crystallinity of the film estimated approximately by Raman Spectroscopy is close to 100%. The fiLm is composed of pure silicon, without impurities such as Cl, H, C, N, and 0, etc. The maximum of its dark-conductivity is i0~ Q ~ cm?and it has excellent stability under illuminative conditions. The absorption coefficient of the film in visible-light range is up to 1 04cm? Moreover, the grain-size of the films on the glass-substrate increases with the depth from the film surface. We infer thereof that, the thicker the film is, the larger the grain-size is. As for the silicon substrate, the completely crystallized poly-silicon films can be gained in lower power. 1 i盓~i~ Compared with other reactive gas sources, we believe that, (a) it is the in-situ chemical cleaning and etching effect and the pre-treatment to the substrate by Cl element that promotes the crystallization of the thin-film, (b) in the initial stage of the deposition, the crystallization rests mainly with the space gas-phase reaction in plasma, therefore the crystallinity is affected by the deposition power, (c) the grains formed in the plasma migrate by diffusion to the surface of the substrate, where all kinds of surface-reaction are carried out, the grains grow and the film is formed finally. In this paper, the energy offered on the surface of substrate is relatively small, i.e., the energy offered to the grains to grow is relatively small, and therefore, the grain-size is small accordingly in general.
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