Barrier-Assisted Plasma Doping for Spatially Selective Resistance Engineering in MoS₂ Transistors

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Atomically thin transition-metal dichalcogenides (TMDs) are key for low-power logic devices.
• Scalable doping techniques are lacking for 2D materials, causing high resistance in 2D transistors.
• Existing methods struggle to achieve region-selective doping, limiting device performance.

Purpose of the Study:

• To develop a scalable and region-selective doping technique for monolayer MoS2.
• To enable degenerate n-type doping of MoS2 while maintaining crystal quality.
• To improve the performance of 2D transistors for future low-power logic applications.

Main Methods:

• A barrier-assisted NH3 plasma process using a pV3D3/Al2O3 dielectric stack.
• The dielectric stack acts as a barrier against plasma damage and a chemical filter for NHx radicals.
• Density functional calculations to understand doping mechanisms and radical interactions.

Main Results:

• Achieved degenerate n-type doping of monolayer MoS2 with an electron density of 4.3 × 10^13 cm^-2.
• Reduced contact resistance to 1.45 kΩ·µm.
• Enhanced mobility and on-current by 5.8-fold with negligible threshold-voltage shift; 260-fold on-current increase with extension-region activation.

Conclusions:

• Barrier-assisted NH3 plasma doping is a viable method for high-performance n-type 2D transistors.
• The process preserves MoS2 crystallinity and enhances device characteristics significantly.
• This technique advances the development of energy-efficient 2D CMOS technology.