InAs/InAsSb type-II superlattice infrared nBn photodetectors and their potential for operation at high temperatures

Abstract

Ga-free InAs/InAsSb type-II superlattice (T2SL) nBn photodetectors with very low dark current are fabricated and characterized. The typical device without antireflection coating and surface passivation has a cut-off wavelength of 13.2 micrometers, quantum efficiency (QE) of 2.5% and a background limited operating temperature of 70 K. Our analysis shows that the anticipated highest operating temperature of a 10.6 micrometer cut-off Ga-free T2SL nBn device can be 108 K, with a potential to reach 135 K if 20% QE or lower noise is achieved.

InAs/GaSb Type-II Superlattice Detectors

“…Such increases in minority carrier lifetimes, along with demonstrated band gap adjustability [109] and suppressed Auger recombination rates [110], suggest lower dark currents for InAs/InAsSb SL detectors in comparison with their InAs/GaSb T2SL counterparts. However, performance, in particular, signalto-noise ratio, of InAs/InAsSb SL-based detectors with pin [111] and nBn [112] architectures was not superior to T2SLbased devices operating in the same wavelength range. This may be attributed to the increased tunneling probability in InAs/InAsSb SL system due to the smaller band offsets [111] and significant concentration of SRH centers in this material [113].…”