Absolute measurement of effective radiative-efficiency in GaAs grown with molecular-beam-epitaxy

In this work, we have decoupled the radiative and nonradiative contributions to recombination by developing analytical models to fit observed non-monoexponential photoluminescence decay and bulk-lifetime temperature-dependence, which has enabled absolute measurement of the effective radiative efficiency and characterization of the dominant defect in lightly doped GaAs samples grown using molecular-beam-epitaxy. The measured effective radiative efficiency values under low level injection conditions range from (88.9 ± 0.1)% and (81.2 ± 0.1)% at 77 K to (0.028 ± 0.001)% and (0.034 ± 0.001)% at 700 K, with 300 K values of (17.3 ± 0.1)% and (10.5 ± 0.1)% in the p-type and n-type samples, respectively. A common defect-signature is observed in the temperature-dependence of the nonradiative lifetime in samples of both doping types, and our measured parameters are consistent with characteristics previously measured for the EL2 defect using deep-level transient spectroscopy.