Highly photosensitive graphene field-effect transistor with optical memory function.

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• Graphene offers ultrawide wavelength photodetection but suffers from low light absorption and fast charge recombination, limiting sensitivity.
• Current graphene photodetector enhancements often involve hybridization, leading to slow response times due to charge accumulation near the graphene channel.

Purpose of the Study:

• To develop a highly photosensitive graphene photodetector with a fast response time and optical memory.
• To investigate the mechanism of light-induced modification of contact resistance for enhanced photosensitivity.

Main Methods:

• Fabrication of a graphene field-effect transistor utilizing gold (Au) oxide on Au electrodes.
• Characterization of device performance, including photosensitivity, response time, noise-equivalent power, and optical memory retention.
• Analysis of light-assisted relaxation of trapped charge at the electrode contacts.

Main Results:

• Achieved a highly photosensitive graphene photodetector with noise-equivalent power of approximately 3 × 10⁻¹⁵ W/Hz¹/².
• Demonstrated a fast response time within milliseconds at room temperature.
• Observed an optical memory function with a retention time of approximately 5 seconds due to light-induced relaxation of trapped charge.

Conclusions:

• Modulating contact resistance via light-assisted charge relaxation at Au oxide/Au electrodes significantly enhances graphene photodetector sensitivity and speed.
• The developed photodetector exhibits promising performance for single-photon detection with integrated optical memory.
• This approach paves the way for advanced graphene-based photodetectors with superior functionalities.