The absorber layers of microcrystalline Si thin-film solar cells with p-i-n structure deposited by plasma-enhanced chemical vapor deposition at 200C were characterized with regard to defect density and the recombination lifetime. The characterization was based upon a comparison of experimentally determined solar cell characteristics with results from numerical device simulations. Evaluation of the dark reverse saturation current indicated a strong dependence of the recombination lifetime, τ, upon the H dilution during deposition. Close to the transition region to amorphous growth, where the highest solar cell efficiencies were observed, τ was a maximum within the crystalline deposition regime and equaled about 80ns. The aspect of a spatially varying defect density within the absorber layer was also addressed by numerical simulations. The results from the analysis of the dark current were compared with electron spin resonance data determined on single layers, which allows conclusions to be drawn regarding the capture cross section of the dominant recombination site in microcrystalline Si.

Defect Density and Recombination Lifetime in Microcrystalline Silicon Absorbers of Highly Efficient Thin-Film Solar Cells Determined by Numerical Device Simulations. T.Brammer, H.Stiebig: Journal of Applied Physics, 2003, 94[2], 1035-42