A comprehensive study of mid-wavelength infrared (MWIR) InAs/InAsSb type-II superlattice (T2SL) photodetectors was performed for full characterization of the E-O performance, reliability, and linearity as well as response speed. Teledyne Judson Technologies has recently developed high operating temperature (HOT) MWIR InAs/InAsSb T2SL large area discrete detectors of 0.25mm and 1mm for front-side illumination. The 50% cut-off wavelength of the detectors ranges from ~5.4 to ~5.7μm at room temperature. For the reliability tests, the T2SL detectors were thermally cycled and humidity tested. Initial testing data showed excellent stability to the temperature and humidity, indicating the T2SL detectors have long-term stability. Linearity, response speed and capacitance were measured at various temperatures and reverse biases. This work presents comprehensive test results, data analysis, and discussion, showing these large size, discrete T2SL detectors have the potential to replace conventional MWIR detector materials.
A comprehensive study of photoresponse linearity characteristics, for high performance short wavelength infrared (SWIR) photodiodes of various materials, is performed. These photovoltaic (PV) detectors were manufactured at Teledyne Judson Technologies (TJT) as standard products, with the state-of-the-art technologies. A broad range of detectors made from several IR materials were selected for linearity tests, including InGaAs (cutoff wavelength from lattice matched 1.7μm to extended wavelength of 1.9-2.6μm), SWIR PV HgCdTe (2.5-2.8μm cutoff), Ge (1.8μm cutoff), and InAs (3.5μm cutoff). Comprehensive linearity test data are presented for each detector material. Characterization of linearity dependence on detector size, operating temperature, reverse bias, and light spot size is studied. Detector size ranges from <0.25mm dia. up to 10mm dia., detector operating temperature from room temperature to thermoelectric cooled (TEC) temperatures, detector bias from 0V up to 10V reverse bias for some materials, and light spot size from 10μm up to 1mm. This work focuses on photocurrent saturation in the high optical power (or photon flux) range. Two saturation mechanisms are investigated, including series resistance effect and Auger recombination effect.