High Performance InGaAs/InP Single-Photon Avalanche Diode Using DBR-Metal Reflector and Backside Micro-Lens

InGaAs/InP single-photon avalanche diodes have proven to be the most practical solution for quantum key distribution and long-distance 3-D imaging. In this paper, to further improve the device performance, a new reflector involving the metal layer and $S\mathrm{i}{O_2}$ / $\text{Ti}{O_2}$ distributed Bragg reflector has been applied together with a micro-lens to increase the absorption efficiency by 58%. The normalized dark count rate is 127 Hz, 361 Hz, and 665 Hz for 10%, 20%, 30% photon detection efficiency, respectively, when it is operated under the gated mode with a pulse repetition rate of 50 MHz and pulse width of 1 ns at 233 K temperature. The normalized dark count rate is nearly an order of magnitude lower than commercial devices at 233 K, reflecting the high performance of the proposed near-infrared single-photon detectors.