High Performance Thin Silicon Solar Cell Structures Grown on Silicon

Abstract

Thin crystalline silicon solar cells can lead to high performance. Factors that will lead to high performance in thin silicon include low back and front surface recombination, light trapping, and minority-carrier lifetimes above 50μS. This work presents new designs of thin silicon cells that use an epitaxially grown absorber on an insulator. The first uses epitaxial lateral overgrowth (ELO) of silicon on silicon, and the second uses epitaxial growth on a silicon-on-insulator (SOI) substrate. Both designs are based on a novel structure that produces a voltage gain. We report the highest performance for solar cells that have been fabricated using silicon oxide as a back reflector layer. Photovoltaic response of ELO absorbers is being improved both for the proposed structure and planar devices.