Characterization of Defects in GaAsyP1-y for III-V/Si Tandem Applications

The impact of threading dislocations (TD) as nonradiative recombination centers on the photovoltaic performance of solar cells, produced using metamorphic (misfit strain relaxed) materials, is well known. However, the specific defect levels/energies associated with this TD-induced recombination are typically unclear. Additionally, metamorphic materials typically introduce other, more subtle features, like surface cross-hatch and non-unform strain profiles, that may also impact performance. This study employs nanoscale correlative cathodoluminescence (CL) with electron channeling contrast imaging (ECCI) to analyze trends observed via macroscale photoluminescence (PL) spectroscopy to elucidate the source of sub-bandgap defect signatures and other optoelectronic metamorphic materials phenomena across the visible bandgap range of the GaAsyP1-y alloy system.