Comparison of GaAsP solar cells on GaP and GaP/Si

Abstract

We demonstrate metamorphic ∼1.7 eV GaAs_xP_1−x (x = 0.71 − 0.73) solar cells on high-quality GaP/Si templates and compare them to cells co-grown on bulk GaP. Both n⁺-emitter/p-base and p⁺-emitter/n-base polarities are explored. Cells with n-type bases demonstrate current-voltage characteristics that are similar to p-type base cells, but with blue-shifted peak quantum efficiencies. Threading dislocation densities for cells on GaP/Si were 0.92 − 1.3 × 10⁷ cm⁻², significantly lower than previous reports but higher than cells grown on bulk GaP. An open-circuit voltage of 1.12 V was obtained for a 1.71 eV cell on Si, leading to a promising bandgap-voltage offset of 0.59 V.