Long and Very Long Wavelength InAs/InAsSb Superlattice Complementary Barrier Infrared Detectors

While the n -type InAs/InAsSb type-II strained layer superlattice (T2SLS) has demonstrated excellent detector and focal plane array performance in the mid-wavelength infrared, it is limited in its attainable quantum efficiency (QE) in the long and very long wavelength infrared due to short hole diffusion length and modest absorption coefficient. We explore InAs/InAsSb T2SLS unipolar barrier infrared detectors that contain p -type absorber layers in order to take advantage of the longer electron diffusion length for QE enhancement. We find that while they can achieve enhanced QE, their dark current characteristics are affected by the presence of metallurgical and surface p - n junctions, and are best operated under lower biasing conditions where the tunneling dark currents are less pronounced. We report results on complementary barrier infrared detector structures that use n -type absorbers, a combination of p - and n -type absorbers, and p -type absorbers, with cutoff wavelengths ranging from 10.0 µm to 15.3 µm.