Manipulation of Photoresponse via Defect-Level Excitations in Metal-Insulator-Semiconductor-Type Two-Dimensional...

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology
• Optoelectronics

Background:

• Metal-insulator-semiconductor (MIS) van der Waals heterostructures are crucial for optoelectronic devices.
• Controlling defects in these heterostructures is key to tuning device performance.
• Previous research highlights the importance of carrier-exciton conversion and defect engineering.

Purpose of the Study:

• To develop a MIS heterostructure photodetector with tunable optoelectronic responses.
• To investigate the role of activated defect states in hexagonal boron nitride (h-BN) layers.
• To demonstrate wavelength-selective photodetection and ultrafast response times.

Main Methods:

• Fabrication of a MIS heterostructure photodetector using monolayer graphene (Gr), h-BN, and monolayer molybdenum disulfide (MoS2).
• Activation of defect states within h-BN layers for controlled interlayer charge transfer.
• Analysis of wavelength-selective photocurrent generation using defect-state modeling and energy-band alignment.

Main Results:

• The device exhibits wavelength-selective photoresponse at 405 nm and 638 nm under visible light.
• A high switching ratio of up to 10^5 and an ultrafast response time of approximately 7-8 μs were achieved.
• Controlled interlayer charge transfer was enabled by activated h-BN defect states.

Conclusions:

• The engineered h-BN defects enable tunable optoelectronic responses in MIS heterostructures.
• The developed photodetector shows potential for applications in photocurrent imaging and optoelectronic logic.
• This work advances the understanding and application of defect engineering in 2D material-based optoelectronics.