Mid-wavelength infrared unipolar nBp superlattice photodetector

We report a Mid-Wavelength Infrared (MWIR) barrier photodetector 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 µm thick p-doped absorber (InAs/GaSb SL) and an n-type contact layer (InAs/GaSb SL). At 80 K, the device exhibited a 50% cut-off wavelength of 5 µm, was fully turned-ON at zero bias and the measured QE was 50% (front side illumination with no AR coating) at 4.5 µm with a dark current density of 4.7 × 10−6 A/cm2 at Vb = 50 mV. At 150 K and Vb = 50 mV, the 50% cut-off wavelength increased to 5.3 µm, and the QE was 54% at 4.5 µm with a dark current of 5.0 × 10−4 A/cm2.