High Quantum Efficiency Mid-Wavelength Infrared Superlattice Photodetector

We report high quantum efficiency (QE) MWIR barrier photodetectors based on the InAs/GaSb/AlSb type II superlattice (T2SL) material system. The nBp design consists of a single unipolar barrier (InAs/AlSb SL) placed between a 4 mu m thick p-doped absorber (InAs/GaSb SL) and an n-type contact layer (InAs/GaSb SL). At 80K, the device exhibited a 50% cut-off wavelength of 5 mu m, was fully turned-ON at zero bias and the measured QE was 62% (front side illumination with no AR coating) at 4.5 mu m with a dark current density of 8.5x10(-9) A/cm(2). At 150 K and V-b=50 mV, the 50% cut-off wavelength increased to 5.3 mu m and the quantum efficiency (QE) was measured to be 64% at 4.5 mu m with a dark current of 1.07x10(-4) A/cm(2). The measurements were verified at multiple AFRL laboratories. The results from this device along with the analysis will be presented in this paper.