Modeling the effects of using polycrystalline substrates for low cost III–V photovoltaics

Abstract

Recent interest in growing high efficiency solar cells on polycrystalline “virtual” recrystallized substrates requires an understanding of the impact of substrate quality and growth nucleation characteristics. This work provides a study on the effects of substrate material, roughness, and crystallinity on efficiency of a GaAs solar cell. A variety of devices were grown on both monocrystalline and polycrystalline GaAs and Ge substrates, and the results were used to predict minority carrier diffusion length as a function of crystal grain size, material quality, and nucleation defect densities.