Traditional InP/InGaAs single-photon avalanche detectors require cooling to approximately 240 K to reduce dark counts, necessitating the use of semiconductor thermoelectric cooling, which increases both volume and power consumption. Through optimization of the material structure and fabrication processes via a single diffusion process, we have developed a high-performance 1550 nm single-photon detector that operates at room temperature (293 K). At a detection efficiency of 20.1%, the dark count rate achieved was 6.82 kHz, with an afterpulse probability of 0.15% and a timing jitter of 120 ps under gated operation. This is the lowest dark count rate reported to date for a 1550 nm single-photon detector operating at room temperature. Furthermore, in a purely passive quenching mode, we obtained a dark count rate of 32.6 kHz with a detection efficiency of 10.3% at room temperature by integrating a SiO2/Cr film resistor through a sputtering process into the detector. Our scheme provides an alternative choice for room-temperature single-photon detectors and should significantly advance their application in compact, low-power devices.

The relationship between the performance of avalanche photodiode (APD) and structural parameters of the absorption, grading, and multiplication layers has been thoroughly simulated and discussed using the equivalent materials approach and Crosslight software. Based on separate absorption, grading, charge, and multiplication (SAGCM) structure, the absorption layer of APD was replaced with InGaAs/GaAsSb superlattice compared to conventional InGaAs/InP SAGCM APD. The results indicated that the breakdown voltage increased with the doping concentration of the absorption layer. When the thickness of the multiplication layer increased from 0.1 μm to 0.6 μm, the linear range of punchthrough voltage increased from 16 V to 48 V, and the breakdown voltage decreased at first and then increased when the multiplication layer reached the critical thickness at 0.35 μm. The grading layer could not only slow down the hole carrier, but also adjust the electric field. The dark current was reduced to about 10 nA and the gain was over 100 when the APD was cooled to 240 K. The response wavelength APD could be extended to 2.8 μm by fine tuning the superlattice parameters. The simulation results indicated that the APD using superlattice materials has potential to achieve a long wavelength response, a high gain, and a low dark current.