All-silicon microring avalanche photodiodes with a >65 A/W response

Area of Science:

• Photonics and Optoelectronics
• Materials Science and Engineering
• Semiconductor Device Physics

Background:

• Silicon photonics is a rapidly growing field, but the lack of high-performance, cost-effective photodetectors remains a challenge.
• Current commercial photodetectors often rely on expensive germanium (Ge) or III-V materials, limiting integration in standard CMOS processes.
• Avalanche photodiodes (APDs) are crucial for high-sensitivity optical detection, but achieving high performance in silicon has been difficult.

Purpose of the Study:

• To report the development of an all-silicon microring resonator (MRR) avalanche photodiode (APD).
• To investigate the mechanisms responsible for the achieved ultrahigh responsivity.
• To demonstrate the potential of silicon APDs as a cost-effective alternative to existing technologies.

Main Methods:

• Fabrication of an all-silicon microring resonator (MRR) structure.
• Characterization of the APD's responsivity (R), dark current, and gain-bandwidth product (GBP).
• Modeling and investigation of the physical mechanisms underlying the high responsivity.
• High-speed testing using open eye diagrams at 1310 nm.

Main Results:

• Achieved an ultrahigh responsivity (R) of 65 A/W.
• Recorded a dark current of 6.5 µA.
• Attained a record gain-bandwidth product (GBP) of 798 GHz at -7.36 V.
• Demonstrated open eye diagrams up to 20 Gb/s at 1310 nm and -7.36 V.
• The device is the first low-cost all-Si APD with potential to compete with Ge- and III-V-based photodetectors.

Conclusions:

• The developed all-Si MRR APD exhibits record-breaking performance metrics, particularly in responsivity and GBP.
• The study elucidates the mechanisms behind the high responsivity, paving the way for further optimization.
• This silicon APD presents a significant advancement, offering a cost-effective and integrable solution for silicon photonics.