Radiometric characterization of long-wavelength infrared type II strained layer superlattice focal plane array under low-photon irradiance conditions

We present the results of the radiometric characterization of an "M" structure long wavelength infrared Type-II strained layer superlattice (SLS) infrared focal plane array (IRFPA) developed by Northwestern University (NWU). The performance of the M-structure SLS IRFPA was radiometrically characterized as a function of photon irradiance, integration time, operating temperature, and detector bias. Its performance is described using standard figures of merit: responsivity, noise, and noise equivalent irradiance. Assuming background limited performance operation at higher irradiances, the detector quantum efficiency for the SLS detector array is approximately 57%. The detector dark density at 80 K is 142 μA/cm ², which represents a factor of seven reduction from previously measured devices.