Waveguide-Integrated van der Waals Heterostructure Mid-Infrared Photodetector with High Performance

Area of Science:

• Photonics and Optical Engineering
• Materials Science
• Semiconductor Devices

Background:

• Silicon photonics is crucial for integrated circuits but limited in mid-infrared (mid-IR) applications.
• A key challenge for mid-IR silicon photonics is the absence of efficient photodetectors with high speed, responsivity, and low noise-equivalent power (NEP).

Purpose of the Study:

• To demonstrate a novel van der Waals (vdW) heterostructure photodetector integrated with silicon-on-insulator (SOI) waveguides for mid-IR operation.
• To address the limitations of existing photodetectors in the mid-IR spectral range for integrated photonic circuits.

Main Methods:

• Fabrication of a vdW heterostructure photodetector by vertically stacking black phosphorus (BP) and molybdenum ditelluride (MoTe2).
• Integration of the BP/MoTe2 vdW heterostructure onto a silicon-on-insulator (SOI) waveguide.
• Characterization of the photodetector's responsivity, modulation speed, switching stability, and noise-equivalent power (NEP) over the 3-4 μm spectral range.

Main Results:

• Achieved high responsivity up to 0.85 A/W in the 3-4 μm spectral range, demonstrating strong light-matter interaction.
• Demonstrated high-speed modulation capability exceeding 10 MHz with excellent switching stability.
• Measured a low noise-equivalent power (NEP) of 8.2 pW/Hz^1/2, indicating a highly sensitive detector.

Conclusions:

• The developed vdW heterostructure photodetector overcomes critical limitations for mid-IR silicon photonics.
• This integrated photodetector is a vital component for advancing mid-IR integrated photonic circuits in fields like healthcare, astronomy, and chemical sensing.
• The device performance paves the way for widespread adoption of mid-IR silicon photonic technologies.