Three-electrode germanium-on-silicon avalanche photodiode array.

Area of Science:

• Optoelectronics
• Semiconductor Devices
• Integrated Photonics

Background:

• Germanium-on-silicon (Ge-on-Si) avalanche photodiodes (APDs) are crucial for optical sensing.
• Complementary metal-oxide semiconductor (CMOS) compatibility is essential for scalable photonic integrated circuits.

Purpose of the Study:

• To introduce a novel bridge-connected three-electrode Ge-on-Si APD array.
• To investigate the performance enhancements offered by the third electrode for near-infrared (NIR) imaging.

Main Methods:

• Fabrication of a three-electrode Ge-on-Si APD array compatible with CMOS processes.
• Electrical and optical characterization of a single three-electrode APD.
• Analysis of the impact of Ge electrode voltage on dark current and responsivity.
• Demonstration of NIR imaging capabilities using the APD array.

Main Results:

• A functional three-electrode Ge-on-Si APD array compatible with CMOS was successfully fabricated.
• Applying a positive voltage to the Ge electrode significantly reduced dark current and increased light responsivity (0.6 A/W to 1.17 A/W at 100 nA dark current).
• The array demonstrated effective near-infrared imaging properties.

Conclusions:

• The three-electrode Ge-on-Si APD design offers improved performance for optical sensing applications.
• This technology is suitable for LiDAR imaging and low-light detection systems.
• The CMOS compatibility facilitates integration into advanced optical systems.