A two-dimensional modeling of the fine-grained polycrystalline silicon thin-film solar cells

A two-dimensional device modeling for polycrystalline silicon thin-film solar cells was performed. A ThRee-dimensional Emitter Based on Locally Enhanced diffusion (TREBLE) concept was applied to evaluate the degree of leveling of the device efficiency. The model assumes a n(+)-p-p(+) junction device of a 3-mum grain size and 10-mum-thick polycrystalline Si columnar structure unit. where the n(+) regions extend along the grain boundaries. The analysis was carried out using ISE-DESSIS, a two-dimensional semiconductor device simulator. It has been found that open circuit voltage could be improved by increasing the base doping level to the optimum value of 10(17) cm(-3). Preferential doping has a beneficial effect on short-circuit current of the cell and a slight influence on open circuit voltage. Conversion efficiency of similar to10% could be expected at the surface, recombination velocity of 10(4) cm / s and dopant diffusion depth along the grain boundary x(gb) = 2.5 mum At base doping similar to10(17) cm(-3) and well-passivated grain boundaries (S-gb = 10(3) cm/s), an efficiency of approximately 12% may be obtained when x(gb) = 3.7 mum. (C) 2002 Elsevier Science B.V. All rights reserved.