A low-noise time-gated single-photon detector in a HV-CMOS technology for triggered imaging

An optical imager for triggered applications is presented. The detector consists of a 10 × 43 array of single-photon avalanche pixels and exhibits an unusual fill-factor of 67%. It has been fabricated in a conventional 0.35 μm HV-CMOS process. The array presents an average dark count rate of 67 kHz at a reverse bias overvoltage of 1 V. Due to the large sensor area of 20 μm × 100 μm, the array is operated in a time-gated mode to reduce the probability of detecting the sensor noise down to 10−4 noise counts per frame with an active period of 4 ns. The crosstalk can be minimized to negligible levels also by means of the time-gated operation. A number of experiments have been conducted on the detector to show that the proposed technique is advantageous in improving the imager signal-to-noise ratio, dynamic range, contrast and spatial resolution.