Monolithic InGaAs-on-silicon short wave Infrared Detector Arrays

We have designed and developed 1, 16, 256, and 512 element linear Monolithic InGaAs-on-silicon Infrared Detector Arrays for the 1 - 3 mu m SWIR band. A methodology of monolithically integrating InGaAs photodetectors and high density complex CMOS readout electronics all on a single silicon substrate has been developed. The innovation consists of an improved ''selective'' epitaxial technique that significantly reduces the misfit dislocation density (< 10(6)/cm(2)) caused by the severe lattice mismatch (8 to 10%) between the InxGa1-xAs (x = 0.53 to 0.82) photodetector's absorption region and the silicon substrate. The individual pixel size of(40x40) and (80x80) mu m(2) exhibits room temperature RoA product of 40 to 45 Omega-cm(2). The InGaAs photodetectors are operated at a zero bias voltage to eliminate leakage current integration, reduce the 1/f noise, and maintain an uniform bias for light detection. The CMOS readout circuitry for each individual pixel consists of an integrating pre-amplifier, a CDS signal processor, and a voltage to current converter. The column scanner for the linear array is a D type shift register with a master clear signal reset once per frame. The master clock signal shifts the bit through the registers one column per clock cycle. When a pixel is selected, the output signal at the voltage to current converter is coupled to a transimpedance amplifier. This amplifier drives the line capacitance of the output bus line to achieve 25 MHz output speed. Power dissipation of less than 100 mW has been demonstrated for 10 MHz operation.