Heterogeneous Defect Domains in Single-Crystalline Hexagonal WS₂.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Single-crystalline monolayer hexagonal tungsten disulfide (WS₂) is a promising 2D material.
• Defects, such as vacancies, significantly influence the electronic and optical properties of 2D materials.

Purpose of the Study:

• To investigate the impact of alternating sulfur-vacancy (SV)-rich and tungsten-vacancy (WV)-rich domains on WS₂ properties.
• To understand the relationship between vacancy type, strain, doping, and electronic/optical characteristics.

Main Methods:

• Raman Spectroscopy
• Scanning Photoelectron Microscopy (SPEM)
• Analysis of electron mobility and photoluminescence

Main Results:

• WS₂ monolayers naturally segment into triangular SV-rich and WV-rich domains.
• WV-rich domains exhibit deep-trap states, leading to electron dedoping.
• Electron mobility and photoluminescence in WV-rich domains are one order of magnitude lower than in SV-rich domains.

Conclusions:

• Vacancy type critically dictates the electronic and optical properties of WS₂.
• Electron dedoping in WV-rich domains significantly impacts material performance.
• Understanding vacancy-induced strain and doping is key for tailoring WS₂ for electronic applications.