InAsSb is a promising material for high operating temperature <i>MWIR</i> detectors. InAsSb <i>p-n</i> junction detectors dark
current is g-r limited in the lower temperature range and diffusion limited in the higher ones. In this work we have
investigated the properties GaSb / InAs<sub>0.91</sub>Sb<sub>0.09</sub> heterostructure and its performance as a sensitive <i>MWIR</i> photodetector.
The heterostructure was obtained by <i>MOCVD</i> growth of lattice matched, unintentionally doped layer of InAsSb on NGaSb
substrate. This rectifying N-n heterostructure has the unique type II broken gap interface. <i>I-V</i> and spectral response
were measured at various temperatures in the range 20-300 K. The <i>BLIP</i> temperature was found to be 180 K. <i>R<sub>0</sub>A</i>
product of 2.5 and 180 Ω•cm<sup>2</sup> were measured at 300 and 180 K, respectively. Dual color detection was demonstrated.
The range of spectral response, due to light absorption in GaSb or in InAsSb can be determined by the applied bias. An
optical gain larger than one was observed at temperatures below 120 K. High detectivity values of 1.3•10<sup>10</sup> and 4.9•10<sup>9</sup>cm•Hz<sup>1/2</sup>W<sup>-1</sup> at 180 and 300 K respectively were measured.