Germanium avalanche receiver for low power interconnects.

Area of Science:

• Photonics and optoelectronics
• Integrated circuit design
• Semiconductor device physics

Background:

• Silicon photonics advances enable on-chip communications.
• High power consumption remains a critical challenge in integrated devices.
• Efficient photodetection is crucial for optical interconnects.

Purpose of the Study:

• To report a novel waveguide avalanche germanium photodiode.
• To demonstrate low-power operation for on-chip communication applications.
• To overcome the power consumption limitations of current integrated photonic devices.

Main Methods:

• Fabrication of a waveguide avalanche germanium photodiode using complementary metal-oxide-semiconductor (CMOS)-compatible processes.
• Characterization of photodiode performance under low reverse bias.
• Evaluation of gain, signal-to-noise ratio (Q-factor), and operational speed at 10 Gbit/s.

Main Results:

• Achieved an intrinsic gain >20 at a low reverse bias of -7 V.
• Maintained a Q-factor >20 dB at 10 Gbit/s without a trans-impedance amplifier for input optical power < -26 dBm.
• Demonstrated a maximum gain >140 for optical powers < -35 dBm.
• Utilized an aggressively shrunk germanium multiplication region.

Conclusions:

• The developed photodiode offers a low-power solution for on-chip communication.
• CMOS-compatible fabrication simplifies integration and reduces costs.
• The device performance paves the way for energy-efficient optical interconnects.