Junction field-effect-transistor-based germanium photodetector on silicon-on-insulator

Area of Science:

• Optoelectronics
• Semiconductor devices
• Photonics

Background:

• Photodetectors are crucial for optical communication and sensing.
• Existing photodetector designs face limitations in sensitivity, speed, and integration.
• Germanium (Ge) offers excellent light absorption properties in the infrared spectrum.

Purpose of the Study:

• To propose and demonstrate a novel Germanium photodetector integrated on a silicon-on-insulator platform.
• To leverage a junction field-effect transistor (JFET) structure for enhanced photodetector performance.
• To achieve high sensitivity and fast response times in a compact device.

Main Methods:

• Fabrication of a Ge photodetector using a JFET structure with a Ge island as the gate.
• Utilizing secondary photoconductivity to modulate the silicon channel conductance upon light absorption.
• Characterization of the device's performance under continuous-wave (cw) and pulsed light conditions.

Main Results:

• Demonstrated a novel Ge photodetector on silicon-on-insulator.
• Observed up to a 33% change in Si channel conductance with only 200 nW optical power at 1.55 microm.
• Achieved rise times as low as 40 picoseconds (ps) in pulsed response tests.
• Enhanced sensitivity due to reduced parasitic capacitance.

Conclusions:

• The proposed Ge photodetector design offers a promising solution for high-performance optical detection.
• The device exhibits excellent sensitivity and fast response, suitable for various photonic applications.
• Integration of Ge with silicon photonics is advanced by this novel JFET-based photodetector.