APIVT Epitaxial Growth on Zone-Melt Recrystallized Silicon: Preprint

Single-junction thin-film silicon solar cells require large grain sizes to ensure adequate photovoltaic performance. Using 2D silicon solar cell simulations on the quantitative effects of grain-boundary recombination on device performance, we have found that the acceptable value of effective grain boundary recombination velocity is almost inversely proportional to grain size. For example, in apolycrystalline silicon thin film with an intragrain bulk minority-carrier lifetime of 1 ?s, a recombination velocity of 104 cm/s is adequate if the grain is 20 ?m across, whereas a very low recombination velocity of 103 cm/s must be accomplished to achieve reasonable performance for a 2-?m grain. For this reason, large grain size on the order of hundreds of ?m is currently a prerequisite forefficient solar cells, although a more effective grain-boundary passivation technique may be developed in the future.