High-efficiency GeSn/Ge multiple-quantum-well photodetectors with photon-trapping microstructures operating at 2 µm

Area of Science:

• Optoelectronics
• Materials Science
• Photonics

Background:

• Germanium-Tin (GeSn) alloys are crucial for optoelectronic applications.
• Efficient photodetectors are needed for 2 µm optical communication.

Purpose of the Study:

• To introduce photon-trapping microstructures into GeSn-based photodetectors.
• To enhance photo detection efficiency and performance at 2 µm.

Main Methods:

• Fabrication of GeSn/Ge multiple-quantum-well (MQW) p-i-n photodiode on a Germanium-on-Insulator (GeOI) architecture.
• Integration of photon-trapping microstructures without additional fabrication cost.
• Characterization of optical and electrical performance, including responsivity and bandwidth.

Main Results:

• Achieved high-efficiency photo detection at 2 µm with a responsivity of 0.11 A/W.
• Demonstrated a four-fold enhancement in photo response compared to non-photon-trapping devices.
• Observed an improved 3-dB bandwidth of 2.7 GHz at -5 V bias.
• Noted an increase in dark current density from 31.5 to 45.2 mA/cm² at -1 V.

Conclusions:

• Photon-trapping microstructures significantly improve GeSn photodetector performance at 2 µm.
• The GeOI platform supports monolithic integration for optoelectronic integrated circuits (OEICs).
• GeSn/Ge MQW photodetectors show great potential for efficient 2 µm communication systems.