Characteristics of carrier localization and their effects on minority carrier lifetime in InAs/In0.5Ga0.5As0.5Sb0.5 type II superlattices

Advanced infrared optoelectronic devices fabricated using antimony-based type-II superlattices have progressed significantly in recent years. However, fundamental challenges remain in the understanding of the exciton recombination mechanism associated with these superlattice structures and in the exploration of efficient methods to suppress the effects of native defects and thus prolong carrier lifetimes. We have investigated the optical properties of high-quality InAs/In0.5Ga0.5As0.5Sb0.5 type-II superlattices in the long-wave infrared band (6–9 μm), where a significant carrier localization phenomenon was observed via temperature- and excitation-power-dependent photoluminescence measurements. The carrier distribution with respect to temperature, including the anomalous temperature dependences of the peak energy, the full width at half maximum, and the integrated intensities, were identified and explained using the localized-state ensemble luminescence model. We also observed a large radiative to nonradiative recombination ratio (∼42.6) by analyzing localized-state ensemble equations in type-II superlattices. Finally, the InAs/In0.5Ga0.5As0.5Sb0.5 superlattice showed long minority carrier lifetimes of up to 847 ns. These results show that the prepared InAs/In0.5Ga0.5As0.5Sb0.5 superlattices have excellent optical properties compared with existing type-II superlattices and have great potential for infrared optoelectronic applications.