Reduction of interfacial recombination in GaInAsSb/GaSb double heterostructures

Minority carrier lifetimes in 0.55 eV band-gap GaInAsSb epitaxial layers that are double capped with GaSb or AlGaAsSb layers were determined using time-resolved photoluminescence. It was found that accumulation of electrons at the p-doped GaInAsSb/GaSb type-II interface contributes significantly to the interfacial recombination velocity S, which was measured to be 3100 cm/s. The use of heavily p-doped GaSb cap layers was proposed to eliminate the potential well of electrons and barrier for holes at the interface. Increasing the GaSb cap doping level from 1×1016 to 2×1018 cm−3 resulted in a 2.7 times reduction of S down to 1140 cm/s. The smallest value of S was determined to be 720 cm/s, which was obtained for structures with AlGaAsSb cap layers that have no valence band offset.