Characterization of a CMOS Geiger photodiode pixel

This paper examines the performance of CMOS avalanche photodiode pixels operated in a Geiger mode. The pixels, called Geiger photodiode (GPD) pixels, convert an incident analog photon flux into a digital count rate. The maximum detection efficiency of the characterized GPD pixel for 632-nm light is 22%. The passively quenched GPD pixel exhibits an after pulsing at excess bias voltages above 2 V, and a minimum in the after-pulsing correction factor, of 0.53, occurs at an excess bias of 5.8 V. The after pulsing increases the fluctuations, or noise, in the count-rate signal. The following expression accurately describes the noise in the characterized GPD pixel, which exhibits a relatively low after-pulsing probability: σ²=n~_dp+n~_ap+2·[n~_dp·n~_ap]¹2/, where σ represents the count-rate fluctuations, the "dp" subscript stands for "detected photons," the "ap" subscript stands for "after pulses," and the n~ represents the "average count rate of" dp, or ap. The noise-equivalent illumination exhibits a minimum of 300 Hz at an operating voltage of 28 V. The best operating voltage for the GPD pixel increases from 28 V with increasing signal intensity.