The next generation of monolithic infrared detector arrays

Abstract

Recently NASA announced an initiative “X-2000¯” whose ultimate goal is “satellite-on-a-chip.” We propose advanced, Monolithic InGaAs-on-silicon Short Wave Infrared (SWIR), and Monolithic InSb-on-silicon Medium Wave Infrared (MWIR) detector arrays for X-2000. To achieve “satellite-on-a-chip” goal, it is imperative to have a fully integrated Focal Plane Array on one wafer substrate, preferably silicon. A (512×512) High Resolution Focal Plane Array structure is proposed that employs a technique to selectively epitaxially grow InGaAs and InSb photodetectors on silicon substrate. Growth of lattice mis-matched InGaAs and InSb layers on silicon substrate is improved by limiting the growth area, selecting appropriately oriented wafers, as well as controlling the growth conditions, and thus, the RoA product, an important parameter of the photodetectors will be enhanced. At 150 K, the expected RoA is 300 to 400 Kohm—sq. cm for InGaAs and 500 to 1,000 Ohm—sq. cm. for InSb. A new CMOS readout circuit will be developed from the present Discovery Semiconductors’ 1D and 2D FPA readout circuits for the (512×512) High Resolution Monolithic InGaAs/InSb-on-Silicon SWIR/MWIR FPA. It has four readout methods suitable for a wide range of RoA product of the IR detectors. The silicon readout circuit will be fabricated by 0.6 um CMOS process technology for obtaining a higher fill factor, readout speed, signal injection, and readout efficiency of the FPA. The above approach addresses the application requirements of NASA’s X-2000 initiative and solves some problems inherent to Hybrid Focal Plane Arrays.