HOT MWIR InAs/InAsSb T2SL discrete photodetector development

Teledyne Judson Technologies (TJT) has developed high operating temperature (HOT) mid-wavelength infrared (MWIR) photodetectors based on InAs/InAsSb type-II superlattice (T2SL) with an electron barrier. Large area discrete detectors of 0.25mm and 1mm diameters were designed and fabricated for front-side illumination. Comprehensive E-O characterization was performed at room temperature and thermo-electric cooled (TEC) temperatures. The unique fabrication process was developed for a quasi-planar structure, enabling simplified fabrication for low-cost large volume production. The detector shows a 50% cut-off wavelength of ~5.5μm at room temperature. Peak responsivity of 2.47 A/W was achieved on 1mm detectors at peak wavelength ~ 4.24μm, -0.3V bias and 295K. Peak quantum efficiency (QE) was 72% with an antireflection coating. The 1mm detectors showed peak detectivity (D*) of 1.9x10⁹ cm-√Hz/W at -0.3V bias, 295K and 10 kHz. Dark current density as low as 1.17 A/cm² was achieved at -0.3V bias and 295K on 1mm detectors. The dark current was diffusion-limited at higher temperatures above ~120K while it was dominated by either tunneling or surface leakage currents at lower temperatures. Similar results were obtained on 0.25mm detectors.