Ge-on-Si single-photon avalanche diode using a double mesa structure

Area of Science:

• Optoelectronics
• Semiconductor device physics

Background:

• Germanium-on-Silicon (Ge-on-Si) technology is crucial for integrated photonics.
• Single-photon avalanche diodes (SPADs) are essential for quantum information and sensing.
• Traditional SPAD designs face challenges with dark current and edge breakdown.

Purpose of the Study:

• To introduce and experimentally validate a novel double mesa structure for Ge-on-Si SPADs.
• To demonstrate performance improvements in dark current, dark count rate, and jitter.
• To achieve high single-photon detection efficiency with low noise.

Main Methods:

• Fabrication of Ge-on-Si SPADs utilizing a double mesa structure.
• Electrical characterization in linear and Geiger modes at low temperatures (110 K).
• Measurement of dark current, dark count rate, single-photon detection efficiency, and jitter.

Main Results:

• The double mesa structure suppresses electric field crowding at mesa edges.
• Dark current reduced by over 260 times at low temperatures compared to single mesa.
• Dark count rate reduced by 100 times at 110 K.
• Achieved 953 kHz dark count rate, 7.3% detection efficiency, and 81 ps jitter.

Conclusions:

• The double mesa design offers significant advantages for Ge-on-Si SPADs.
• This structure leads to substantially reduced dark counts and improved operational stability.
• The demonstrated performance metrics establish a new benchmark for Ge-on-Si SPADs.