High-Performance MWIR HgCdTe on Si Substrate Focal Plane Array Development

The development of low noise-equivalent differential temperature (NEDT), high-operability midwave infrared (MWIR) focal plane arrays (FPAs) fabricated from molecular beam epitaxial (MBE)-grown HgCdTe on Si-based substrates is reported. High-quality n-type MWIR HgCdTe layers with a cutoff wavelength of 4.90 mu m at 77 K and a carrier concentration of 1-2 x 10(15) cm(-3) were grown on CdTe/Si substrates by MBE. Highly uniform composition and thickness over 3-inch areas were demonstrated, and low surface defect densities (voids similar to 5 x 10(2) cm(-2), micro-defects similar to 5 x 10(3) cm(-2)) and etch pit density (similar to 3.5 x 10(6) cm(-2)) were measured. This material was used to fabricate 320 x 256, 30 mu m pitch FPAs with planar device architecture; arsenic implantation was used to achieve p-type doping. Radiometric and noise characterization was also performed. A low NEDT of 13.8 m K at 85 K for a 1 ms integration time with f/#2 optics was measured. The NEDT operability was 99% at 120 K with a mean dark current noise of 8.14 x 10(-13) A/pixel. High-quality thermal images were obtained from the FPA up to a temperature of 150 K.