High-Performance WSe₂ Top-Gate Devices with Strong Spacer Doping.

Area of Science:

• Materials Science
• Nanotechnology
• Solid-State Physics

Background:

• High-performance two-dimensional (2D) transistors often require complex structures due to limitations in contact and spacer doping.
• Existing methods for 2D device fabrication face challenges in achieving efficient doping, impacting device performance and scalability.

Purpose of the Study:

• To investigate the efficacy of chloroauric acid (HAuCl4) as a p-dopant for tungsten diselenide (WSe2) monolayers in transistors.
• To explore novel doping strategies for 2D transistors to overcome fabrication challenges and enhance device characteristics.

Main Methods:

• Utilized chloroauric acid (HAuCl4) as a strong p-dopant for WSe2 monolayers.
• Fabricated and characterized transistors incorporating HAuCl4 doping and investigated carrier diffusion phenomena.
• Optimized spacer length for doping to achieve normally off device operation.

Main Results:

• Achieved a record-low contact resistance of 0.7 kΩ·μm at a doping concentration of 1.76 × 10^13 cm^-2.
• Discovered an extrinsic carrier diffusion phenomenon in the HAuCl4-WSe2 system.
• Demonstrated the successful fabrication of a normally off, high-performance underlap top-gate device without additional gating in contact/spacer regions.

Conclusions:

• Chloroauric acid (HAuCl4) is an effective p-dopant for WSe2 monolayers, significantly improving contact resistance.
• The discovered carrier diffusion phenomenon offers new possibilities for device design and optimization.
• This doping approach enables the creation of advanced, high-performance 2D transistors with simplified structures.