Point defects in carbon-rich polycrystalline silicon

The behavior of intrinsic point defects in silicon is still an unresolved problem. As they interact with other impurities and influence their diffusion they therefore, affect electronic properties of the material. Of particular importance is the behavior of intrinsic point defects in poly-Si due to structural defects, such as dislocations, grain boundaries, and light impurities often present in very high concentrations. We have shown by infrared analysis that in carbon supersaturated edge-defined film-fed grown poly-Si self-interstitial generation is significantly retarded in comparison to single crystals. Besides structural defects, carbon was considered responsible for this behavior. This finding led to the conclusion that carbon rich poly-Si should be a vacancy rich material, as has been found in single crystals. We have shown by deep level transient spectroscopy measurements performed on irradiated poly-Si, that vacancy generation is greatly enhanced. Carbon rich poly-Si bulk accommodated much more vacancies produced by irradiation than could be revealed in as-irradiated samples.