MIS-stimulated back-surface passivation of interdigitated back-contacts solar cells

The possibility of surface recombination losses reduction on the rear side of interdigitated back-contact solar cells by field-effect passivation is investigated. To provide field-effect passivation, an additional biased metal/insulator/semiconductor (MIS) structure is formed between n++ and p+-doped regions. The source of the bias is the potential that appears in the solar cell under illumination. Two-dimensional (2D) numerical simulations were performed to determine the best passivation conditions. In particular, the influence of symmetric and asymmetric capture cross sections for electrons and holes at the rear side of the cell is simulated and the advantage of symmetric capture cross section for this type of passivation is discussed. Experimental and calculated data are compared for Si/SiO2 interface.