THEORETICAL MAXIMAL EFFICIENCY FOR A SILICON SOLAR-CELL WITH A 2 INFRARED-PHOTON ABSORPTION IN AN INSERTED SUBSTRUCTURE

One of the possible optimized device designs far silicon solar cell ph otocurrent enhancement, consists of a cell having an inserted sub-stru cture with extrinsic gap levels. A middle gap impurity and defect leve l band may actually allow a two infrared photon absorption. The juncti on near local defect layer design (Li et al., 1992) was assumed to enh ance the sub-band-gap light absorption but it also enhances the recomb ination mechanisms strongly. Kuznicki (1993) has proposed another desi gn with an L-H interface insertion at the edges of a continuous sub-st ructure to avoid extra recombination. The maximal photocurrent due to an additional infrared absorption calculated in this way is smaller th an Delta I-ph = 16.8 mAcm(-2). In the case when the widths of the abso rbing sub-structure are negligible compared to the width of the emitte r, the simulated maximal efficiency can vary from 30.87 mW cm(-2) to 4 0.51 mW cm(-2).