Highly Efficient Near-Infrared Detector Based on Optically Resonant Dielectric Nanodisks.

Area of Science:

• Photonics and Optoelectronics
• Materials Science
• Semiconductor Devices

Background:

• Photodetectors are crucial for near-infrared (NIR) applications.
• Germanium (Ge) photodetectors offer NIR sensitivity but face a speed-responsivity trade-off.
• Achieving high-speed and high-quantum efficiency simultaneously is a persistent challenge.

Purpose of the Study:

• To design and realize a dielectric metasurface composed of subwavelength germanium PIN photodetectors.
• To overcome the inherent limitations of conventional Ge photodetectors for NIR photon detection.
• To enhance both the speed and quantum efficiency of photodetectors.

Main Methods:

• Fabrication of a dielectric metasurface array of subwavelength germanium PIN photodetectors.
• Engineering of optical resonant modes within intrinsic Ge disks to enhance light absorption.
• Characterization of photodetector performance, including bandwidth, responsivity, and operational bias.

Main Results:

• Achieved a high-speed photodetector with a 65 GHz bandwidth due to the subwavelength pixel size.
• Obtained high quantum efficiency for NIR illumination by localizing optical energy.
• Demonstrated small junction capacitance and potential for zero/low bias operation.

Conclusions:

• All-dielectric metasurfaces offer a promising approach to significantly improve photodetector performance.
• The proposed Ge metasurface photodetector design effectively addresses the speed-efficiency trade-off.
• This technology advances the development of high-performance NIR photodetectors.