Optimization of the Nonradiative Lifetime of Molecular-Beam-Epitaxy (MBE)-Grown Undoped GaAs/AlGaAs Double Heterostructures (DH)

In this report, we present results of an ongoing study aimed at measuring and optimizing the nonradiative lifetime and the internal radiative quantum efficiency of molecular beam epitaxy MBE-grown gallium arsenide GaAs solar cells that are grown at the U.S. Army Research Laboratory ARL using different substrate growth temperatures and arsenic Asgallium Ga flux ratios to determine the growth parameters that maximize the bulk GaAs minority carrier nonradiative lifetime. We report a significant increase in the nonradiative lifetime and the internal radiative quantum efficiency of MBE-grown GaAsaluminum gallium arsenide AlGaAs double heterostructure DH structures grown at ARL with a growth temperature of 595 C and an AsGa flux ratio 15. Our results show that the nonradiative lifetime and internal radiative quantum efficiency of the DH structures grown using these parameters are comparable to those of the highest quality reported MBE-grown GaAs.