Laser Annealed Boron Implanted Silicon Solar Cells

Abstract

The use of high power laser pulses is being explored as a technique for annealing radiation damage in ion implanted silicon prior to the fabrication of solar cells. Extensive studies have been carried out to compare laser and conventional thermal annealing characteristics using /sup 11/B/sup +/ (35 keV) implanted silicon (100) crystals. Our results show that laser annealing can completely restore electrical activity in the implanted layer with little or no degradation of the minority carrier lifetime in the substrate. Moreover, the residual disorder in the implanted layer is drastically reduced in comparison to that observed after conventional thermal annealing. Solar cells have been fabricated using /sup 11/B/sup +/ (35 keV) implanted, laser annealed, 80 ..cap omega..-cm (100) Si. A substantial improvement in cell parameters is observed in laser annealed cells compared to similar cells fabricated using conventional thermal annealing. Results are presented to compare laser and thermally annealed ion implanted cells, and to compare these to cells fabricated using standard diffusion techniques. Possible reasons for the improvement in the laser annealed cells compared to the thermally annealed ion implanted cells are discussed.