High-Performance WSe₂ Photodetector Based on a Laser-Induced p-n Junction

Area of Science:

• Materials Science
• Nanotechnology
• Condensed Matter Physics

Background:

• Two-dimensional (2D) heterojunctions are crucial for nanoelectronic and optoelectronic devices.
• Fabricating these heterojunctions often involves complex alignment and introduces defects.
• Engineering precise p-n junctions in 2D materials remains a challenge.

Purpose of the Study:

• To develop a novel, defect-controlled method for creating lateral p-n junctions in 2D materials.
• To investigate the feasibility of using a laser scanning technique for selective doping.
• To demonstrate the application of these engineered junctions in self-powered photodetectors.

Main Methods:

• Utilized a laser scanning technique to construct a lateral WSe2 p-n junction.
• Identified laser-induced oxidation product (WOx) as the source of p-type doping.
• Characterized the electrical and optoelectronic properties of the laser-scanned WSe2.

Main Results:

• Achieved selective p-type doping in the laser-scanned region of WSe2.
• Observed a transition from ambipolar to unipolar p-type behavior in WSe2 after laser scanning.
• Demonstrated a significant photocurrent at the WSe2 p-n junction.

Conclusions:

• The laser scanning technique offers a selective and defect-controlled method for fabricating WSe2 p-n junctions.
• A self-powered WSe2 photodetector with high photoswitching ratio (10^6), responsivity (800 mA/W), and fast response time was successfully fabricated.
• This laser-doping approach shows great promise for future electronic and optoelectronic applications.