Passivation Technologies for Improved Operability and Radiation Tolerance in VLWIR HgCdTe Focal Plane Arrays

HgCdTe, with its high quantum efficiency, remains the material of choice for most high-performance infrared detector applications. By varying its alloy composition, HgCdTe can be used for short wavelength to very long wavelength infrared (VLWIR); however, its use in VLWIR (12-16 microns) applications is problematic, even when grown on lattice-matched CdZnTe substrates, due to material and substrate quality issues. Ongoing work by Amethyst Research is proving hydrogenation effective in passivating defects and improving carrier lifetime/mobility in HgCdTe/Si infrared focal plane arrays (IRFPAs), offering the potential for increased producibility of large arrays, extended effective spectral response to longer wavelengths, and reduced cooling requirements. Recent research by Amethyst suggests that hydrogenation may also be effective in defect mitigation and the attendant operability improvements of HgCdTe/ZnCdTe focal plane arrays. There is also evidence to suggest that hydrogenation may improve radiation hardness of the HgCdTe/ZnCdTe, providing a self-healing material with immunity to a variety of defect sources. Amethyst proposes to investigate hydrogenation of HgCdTe/ZnCdTe for defect passivation and radiation hardening. Amethyst’s collaboration with BAE, Raytheon Vision Systems and Teledyne Imaging Sensors (formerly Rockwell Scientific), the country’s major IRFPA manufacturers, will ensure rapid transition of this manufacturing technology to MDA platforms.