Study on the dark signal of near-infrared InGaAs linear detector arrays

The dark currents of near-infrared InGaAs detectors were studied by I-V curves, the relations between the dark currents of InGaAs detectors and the dark signals of InGaAs FPA were analyzed. The result shows that the dark current is dominated by diffusion current at -100 mV reverse bias down to about 273 K, the dark current is dominated by generation-recombination current at -400 mV reverse bias down to about 273 K, the effect of interface current on the dark current increase at the smaller bias voltage. The dark currents of InGaAs linear detectors is the major reason of the dark signal output of InGaAs FPA, the smallest dark current among InGaAs linear detectors is about 0.92 pA at -3 mV reverse bias, which cause the corresponding electrons of 2.87 × 10⁵ in FPA and the corresponding dynamic range of 56 dB. Pixel-to-pixel variations of CTIA in ROIC result in variation of the actual bias voltages applied to the diodes which increase non-uniformity of the dark signal output of InGaAs FPA. The result shows that the further decrease of the dark current of InGaAs detectors is an improvet approach to improving the dynamic range of InGaAs FPA.