Superlinear Luminescence and Enhancement of Optical Power in GaSb-based Heterostructures with High Conduction-Band Offsets and Nanostructures with Deep Quantum Wells

Abstract

Heterostructures and nanostructures with quantum wells (QWs) based on the GaSb/InAs/AlSb system are promising for developing optoelectronic devices (light-emitting diodes, lasers, photodetectors) because they cover the mid-infrared spectral range (1.6-5.0 μm), where absorption bands of many natural and industrial gases and other substances exist (CO2, CO, CH4, H2O, H2S, NH3, and many others). However, the optical power and quantum efficiency of light-emitting diodes (LEDs) based on the narrow-gap semiconductor alloys (InAsSb, InGaAsSb) are not sufficiently high and are limited by nonradiative Auger recombination. It was shown that Auger recombination can be suppressed at the type-II abrupt heterointerface and in nanostructures with deep QWs. A system of InGaAsSb/GaSb alloys is also of interest due to the fact that, by varying the composition of the layers, one can obtain type-II heterojunctions with both staggered and broken-gap alignment. A specific feature of type-II heterojunctions is that self-aligned QWs on both sides of the boundary in which charge carriers are localized maintain the electrons and holes spatially separated. In such structures it is possible to obtain emission at longer wavelengths because of tunneling transitions of charge carriers through the heteroboundary. Due to the interaction of carriers with the heteroboundary in type-II heterostructures, the Auger recombination process is thresholdless, since the conservation law for the momentum component perpendicular to the heteroboundary is not fulfilled. In this case, the Auger recombination rate is a power function of temperature.