A novel approach to characterization of bottom sub-cell in multijunction solar cell using photoluminescence.

Abstract

Multijunction solar cells grown on group IV substrates using III-V compounds are very promising due to their high efficiency (over 40%). Further development of these structures is mainly focused on III-V layers while bottom sub-cell based on p-n junction in the substrate is disregarded. However, high temperatures required for III-V epitaxy as well as diffusion over III-V/IV interface may affect minority carrier lifetime in the substrate. GaAs/GaInP/(AlAs)/Ge heterostructures were grown by MOCVD. Thermal annealing at the conditions of triple-junction solar cells was performed and photoluminescence spectra for these structures were investigated.