Total dose test with γ-ray for silicon single photon avalanche diodes

Gamma-ray (γ-ray) radiation for silicon single photon avalanche diodes (Si SPADs) is evaluated, with total dose of 100 krad(Si) and dose rate of 50 rad(Si)/s by using 60Co as the γ-ray radiation source. The breakdown voltage, photocurrent, and gain have no obvious change after the radiation. However, both the leakage current and dark count rate increase by about one order of magnitude above the values before the radiation. Temperature-dependent current-voltage measurement results indicate that the traps caused by radiation function as generation and recombination centers. Both leakage current and dark count rate can be almost recovered after annealing at 200 °C for about 2 hours, which verifies the radiation damage mechanics.