Researchers Develop Silicon Single-Photon Detector with 84.4% Photon Detection Efficiency and Flexible Operation Modes

Researchers from the University of Science and Technology of China, led by Mr. Dong An, have developed a new silicon single-photon detector (Si SPD) that achieves a photon detection efficiency (PDE) of up to 84.4% at 785 nm. The device supports multiple operation modes, including free-running, gating, and hybrid modes.

Silicon single-photon detectors are used in quantum photonics and single-photon imaging to detect individual photons in the visible spectrum. Applications in these fields require high PDE to collect photons effectively. While Si SPDs offer compact size and ease of operation, achieving efficiencies above 80% has remained challenging.

The team addressed this by optimizing the device's semiconductor structure and electronic readout circuit. They designed a thick-junction silicon single-photon avalanche diode (SPAD) featuring a doping-compensated avalanche region to reduce noise and improve electric-field uniformity. A backside-illumination architecture increases the probability that absorbed photons trigger an avalanche.

To complement this structure, the researchers developed a 50-volt active-quenching readout circuit that enables rapid switching between armed and idle states, maximizing avalanche probabi...