Influence of carrier localization on minority carrier lifetime in InAs/InAsSb type-II superlattices

A long minority carrier lifetime of 12.8 μs in a mid-wavelength infrared InAs/InAsSb type-II superlattice is observed at 15 K using time-resolved photoluminescence technique. The long carrier lifetime is due to carrier localization, which is confirmed by a 3 meV blue shift of the photoluminescence peak energy and the monotonic decrease of lifetime with increasing temperature from 15 K to 50 K, along with an increased photoluminescence linewidth below 40 K. In contrast, no carrier localization is observed in a long-wavelength infrared type-II superlattice at the same temperatures. Modeling results show that carrier localization is stronger in shorter period (9.9 nm) mid-wavelength infrared superlattices as compared to longer period (24.2 nm) long-wavelength infrared superlattices, indicating that the carrier localization originates mainly from InAs/InAsSb interface disorder. Although carrier localization enhances carrier lifetimes, it also adversely affects carrier transport, and thus should be carefully considered in the design and evaluation of InAs/InAsSb type-II superlattice photodetectors.