Understanding and Controlling Vanadium Doping and Sulfur Vacancy Behavior in Two-Dimensional Semiconductors: Toward...

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Transition-metal dichalcogenide (TMD) monolayers are crucial for optoelectronics, catalysis, and quantum technologies.
• Doping TMDs allows precise tuning of their properties, but dopant-defect interactions complicate outcomes.
• Sulfur vacancies are common intrinsic defects in TMDs that interact with dopants.

Purpose of the Study:

• To investigate the effect of varying p-type vanadium (V) doping concentrations in tungsten disulfide (WS2) monolayers.
• To understand the interplay between V dopants and sulfur vacancies in WS2.
• To elucidate the mechanisms governing doping behavior and property modulation in WS2.

Main Methods:

• Systematic variation of vanadium doping density in WS2 monolayers.
• Photoluminescence (PL) microscopy (excitation- and temperature-dependent).
• Atomic-resolution scanning transmission electron microscopy (STEM).
• First-principles calculations.

Main Results:

• Low V concentrations enhanced WS2 optical properties (increased photoluminescence) without new electronic states.
• High V concentrations promoted vanadium-sulfur vacancy complexes, generating tunable midgap states.
• Attractive interactions between p-type V dopants and n-type monosulfur vacancies were identified.

Conclusions:

• Dopant-defect interactions, specifically V and sulfur vacancies, significantly influence WS2 properties.
• The balance between enthalpic and entropic effects governs doping outcomes in TMDs.
• This work provides a pathway for rational design of doping strategies for advanced TMD applications.