Improvement of infrared detector performance in carrier depleted strained layer type II superlattices

The combined effects of suppressing Auger recombination in strained layer superlattices (SL), photon recycling, and the suppression of both Auger and radiative recombination with carrier depletion are calculated quantitatively for a 11 mu m 35.9 Angstrom InAs/15.7 Angstrom In0.225Ga0.775Sb and a 3.5 mu m 16.7 Angstrom InAs/35 Angstrom In0.25Ga0.75Sb SL operating at temperatures between 200 and 300 K. The results are compared to their HgCdTe counterparts. The SL performance is better in all cases. However, the carrier concentrations required for background limited performance (300 K, 2 pi field of view), ranging between about 1 x 10(13) and 4 x 10(13) cm(-3) at 300 K in both SLs, are seen to be impractically low. The carrier concentration in a 11 mu m photon detector yielding equivalent performance to a 300 K thermal detector is about 10(14) cm(-3) Large performance enhancement using carrier depletion therefore appears impractical even in optimized SLs. (C) 1997 American Institute of Physics.