Estimation of the Upper Limit of the Minority-Carrier Diffusion Length in Multicrystalline Silicon: Limitation of the Action of Gettering and Passivation on Dislocations

摘要

We discuss the effect of gettering and hydrogen passivation on the recombination activity of contaminated dislocations. It is demonstrated that a residual amount of dislocation states in the order of 104 cm"1 remains active even under optimum processing conditions, which sets an upper limit to the diffusion length in dislocated solar-grade silicon. Based on an analysis of DLTS investigations on misfit dislocations, we show that impurities may either be accommodated in the dislocation core or in a cloud around the dislocation. We suggest that the former are at the origin of the limited efficiency of gettering and passivation.