Silicon single-photon detectors (Si SPDs) with low cost and ease of operation are widely used for detecting single photons in the visible spectrum. However, photon detection efficiency (PDE) is important for effectively collecting photons, highlighting the need for high-efficiency detectors. Now, researchers have developed a novel Si SPD that reaches 84.4% PDE at 785 nm. It provides a practical solution for quantum communication and imaging applications that rely on detecting weak light signals.

Silicon single-photon detectors (Si SPDs) play a central role in quantum photonics and single-photon imaging for detecting single photons in the visible spectrum. Many of these applications demand high photon detection efficiency (PDE) for effectively collecting photons. While Si SPD have compact size and are easy to operate, boosting their efficiency above 80% has been a challenge.

To address this, Mr. Dong An from University of Science and Technology of China and his team developed a new Si SPD by optimizing both the device’s semiconductor structure and its electronic readout. Their study was published in IEEE Journal of Selected Topics in Quantum Electronics, as part of its recently released Special Issue on Quantum Materials and Devices.

They designed a thick-junction silicon single-photon avalanche diode (SPAD) with a doping-compensated avalanche region to reduce noise and improve electric-field uniformity. A backside-illumination architecture increases the likelihood that each absorbed photon triggers an avalanche. To support this architecture, the researchers built a 50-volt active-quenching readout circuit that rapidly switches the detector between armed and idle states. This design maximizes avalanche probability and enables operation across multiple detection modes. The full SPD module comprising of SPAD, readout circuit, and affiliated circuits measures just 9 × 10 × 3 cm and integrates temperature stabilization and universal serial bus-based control.

“Our new design with a remarkable PDE of up to 84.4% at 785 nm helps silicon detectors achieve their highest detection efficiency while preserving its compact module, enable flexible operation in free-running, gating, and hybrid modes,” says Mr. An.  

At 268 K, the detector achieves a dark count rate of 260 counts per second, an afterpulse probability of 2.9%, and a timing jitter of 360 picoseconds. Cooling the device reduces dark counts further, while higher temperatures lower afterpulsing. The team notes that minimizing timing jitter remains an area for future improvement.

“Our study through the development of a high-efficiency Si SPD module provides a practical

solution for quantum photonics and single-photon imaging applications demanding ultra-high-efficiency Si SPDs with flexible operation modes,” says Mr. An.   

Overall, the findings suggest that carefully engineered silicon structures, combined with advanced quenching electronics, can significantly raise detector performance and expand the capabilities of photon-based technologies.

Reference

Funding information

This work was supported by the Innovation Program for Quantum Science and Technology (Grant Nos. 2021ZD0300800 and 2021ZD0300804), the National Natural Science Foundation of China (Grant Nos. 62175227 and 62405305), and the Fundamental Research Funds for the Central Universities (Grant No. WK9990000161).