High-Performance Long-Wavelength Infrared HgCdTe Focal Plane Arrays Fabricated on CdSeTe Compliant Si Substrates

摘要

At the U.S. Army Research Laboratory, a new ternary semiconductor system $ hbox{CdSe}_{x}hbox{Te}_{1 - x}/hbox{Si}(hbox{211})$ is being investigated as an alternative substrate to bulk-grown CdZnTe substrates for HgCdTe growth by molecular beam epitaxy. Long-wavelength (LW) photovoltaic devices fabricated on this compliant substrate material show diffusion limited performance at 78 K, indicating a high-quality material. The measured $hbox{R}_{o}hbox{A}$ at 78 K on $lambda_{rm co} = hbox{10} muhbox{m}$ material is on the order of 340 $Omega cdot hbox{cm}^{2}$. In addition to single devices, we have fabricated 256 $times$ 256 2-D arrays with a 40-$muhbox{m}$ pixel pitch on LW-HgCdTe grown on $hbox{CdSe}_{x}hbox{Te}_{1 - x}/hbox{Si}(hbox{211})$ compliant substrates. The data show an excellent quantum efficiency operability of 99% at 78 K under a tactical background flux of $hbox{6.7} times hbox{10}^{15} hbox{ph/cm}^{2}hbox{s}$ . The most probable dark current at peak distribution is $ hbox{5.5} times hbox{10}^{9} hbox{e-/s}$ and is very consistent with the measured $hbox{R}_{o}hbox{A}$ values from single devices. This work demonstrates that $hbox{CdSe}_{x}hbox{Te}_{1 - x}/hbox{Si}(hbox{211})$ substrates provid-ne a potential roadmap for more affordable robust third-generation focal plane arrays.