DC Characterization of Highly Sensitive 1 by 128 NIR Photodetector Arrays with CMOS Readout IC

Optical sensitivity improved InGaAs/InP heterojunction phototransistor (HPT) 1times128 one dimensional array chip and its CMOS readout IC have been designed and characterized for low light signal detection. We also present epitaxial structures and equivalent model to optimize the optical gain and shunt resistance characteristics. The device operation mechanism and experimental results are discussed. The experimental results show that our device has an optical sensitivity of 46 A/W. This high value of sensitivity originates from the optical gain-enhanced device structure. The proposed HPT also has hundreds of KOmega shunt resistance with high optical sensitivity under low illumination situation, which is enough for effective signal conversion through trans-impedance amplifier circuit.