Multimodal Photodiode and Phototransistor Device Based on Two-Dimensional Materials.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Optoelectronics

Background:

• Two-dimensional (2D) materials exhibit strong light-matter interactions, making them suitable for optoelectronic devices.
• Existing photodetector designs, such as lateral phototransistors and vertical photodiodes, offer distinct advantages like high gain or fast response, respectively.
• Integrating these functionalities into a single device has been a challenge.

Purpose of the Study:

• To develop a multimodal photodetector platform based on 2D materials.
• To combine the high optical gain of a phototransistor with the fast response of a photodiode within a single device.
• To enable dynamic selection between these operational modes.

Main Methods:

• Fabrication of a multimodal photodetector using a multilayered transition-metal dichalcogenide flake.
• Transferring the 2D material onto metal electrodes with a transparent gate electrode.
• Utilizing the channel region as a phototransistor and the electrode region as a vertical Schottky photodiode.

Main Results:

• Demonstration of a single 2D material device functioning as both a phototransistor and a photodiode.
• Achieved high optical gain in phototransistor mode and fast response in photodiode mode.
• Successful dynamic switching between modes by controlling drain and gate voltages.

Conclusions:

• The developed platform offers a versatile solution for optoelectronic applications requiring both high gain and fast response.
• This multimodal approach leverages the unique properties of 2D materials for advanced photodetector designs.
• The ability to dynamically select operating modes enhances device flexibility and performance.