Chloride molecular doping technique on 2D materials: WS2 and MoS2

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Achieving low-resistivity metal-semiconductor (M-S) contacts is a critical challenge for 2D transition metal dichalcogenides (TMDs).
• High contact resistance (Rc) hinders the performance of TMD-based nanoelectronic devices.

Purpose of the Study:

• To develop an effective doping technique to reduce contact resistance in few-layer WS2 and MoS2.
• To demonstrate the impact of this doping on the performance of field-effect transistors (FETs).

Main Methods:

• A chloride molecular doping technique was employed to treat few-layer WS2 and MoS2.
• Contact resistance (Rc) was measured before and after doping.
• Few-layer WS2 field-effect transistors (FETs) were fabricated and characterized.

Main Results:

• Contact resistance (Rc) in WS2 was reduced to 0.7 kΩ·μm and in MoS2 to 0.5 kΩ·μm.
• The reduction in Rc is attributed to high electron-doping density and a narrowed Schottky barrier width.
• Doped WS2 FETs exhibited a high drain current (380 μA/μm), on/off ratio (4 × 10^6), and mobility (60 cm^2/(V·s)).

Conclusions:

• Chloride molecular doping is a highly effective method for reducing contact resistance in TMDs.
• This technique facilitates the development of high-performance 2D nanoelectronic devices.
• The study provides a viable route for overcoming a key obstacle in TMD research.