Single photon detector with a mesoscopic cycling excitation design of dual gain sections and a transport barrier

Conventional semiconductor single photon detectors (SPDs) are Geiger-mode avalanche photodiodes made of high-quality crystalline semiconductors and require external quenching circuits. Here we report a design of an SPD having dual gain sections to obtain mesoscopic cycling excitation and an amorphous/crystalline heterointerface to form an electron transport barrier that suppresses gain fluctuations. The dual gain sections comprise a crystalline silicon n/p junction and a thin layer of amorphous silicon. At 100 MHz, the device shows single photon detection efficiency greater than 11%, self-recovery time of less than 1 ns, and an excess noise factor of 1.22 at an average gain around 75,000 under 8.5 V bias.