Fabrication of High Operating Temperature (HOT), Visible to MWIR, nCBn Photon-Trap Detector Arrays

摘要

We describe our recent efforts in developing visible to mid-wave (0.5 urn to 5.0 μm) broadband photon-trap InAsSb-based infrared detectors grown on GaAs substrates operating at high temperature (150-200K) with low dark current and high quantum efficiency. Utilizing an InAsSb absorber on GaAs substrates instead of an HgCdTe absorber will enable low-cost fabrication of large-format, high operating temperature focal plane arrays. We have utilized a novel detector design based-on pyramidal photon trapping InAsSb structures in conjunction with compound barrier-based device architecture to suppress both G-R dark current, as well as diffusion current through absorber volume reduction. Our optical simulation show that our engineered pyramid structures minimize the surface reflection compared to conventional diode structures acting as a broadband anti-reflective coating (AR). In addition, it exhibits ＞ 70-80% absorption over the entire 0.5 μm to 5.0 μm spectral range while providing up to 3x reduction in absorber volume. Lattice-mismatched InAs_(0.82)Sb_(0.18) with 5.25 μm cutoff at 200K was grown on GaAs substrates. 128×128/60μm and 1024×1024/18μm detector arrays that consist of bulk absorber as well as photon-trap pyramid structures were fabricated to compare the detector performance. The measured dark current density for the diodes with the pyramidal absorber was 3x lower that for the conventional diode with the bulk absorber, which is consistent with the volume reduction due to the creation of the pyramidal absorber topology. We have achieved high D (＞ 1.0 × 10~(10) cm √Hz/W) and maintain very high (＞ 80 %) internal quantum efficiency over the entire band 0.5 to 5 μm spectral band at 200K.