Photoluminescence Induced by Substitutional Nitrogen in Single-Layer Tungsten Disulfide

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Defects in 2D materials significantly alter electronic and optical properties.
• These defects offer applications like controllable doping and single-photon emission.

Purpose of the Study:

• Investigate defects induced by remote N2 plasma in single-layer WS2.
• Characterize the resulting photoluminescence (PL) properties.
• Determine the origin and implications of observed PL peaks.

Main Methods:

• Exposure of single-layer WS2 to remote N2 and Ar plasma.
• Photoluminescence (PL) spectroscopy at low temperatures.
• First-principles calculations.

Main Results:

• Remote N2 plasma created a distinct low-energy PL peak at 1.59 eV in WS2.
• This peak was absent with Ar plasma and dependent on N2 exposure dose.
• The 1.59 eV PL peak is attributed to sulfur-nitrogen substitution defects.
• Optimal defect concentration for the PL peak was around 2.0% sulfur deficiency.

Conclusions:

• Substitutional nitrogen defects in WS2 act as potential single-photon emitters.
• The intensity of the 1.59 eV PL peak can monitor substitutional nitrogen doping levels.
• Nitrogen plasma offers a method to engineer optical properties of 2D materials.