Complementary Doping Strategy for Achieving Low Contact-Resistance in p-Type Two-Dimensional Field-Effect...

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• High-performance complementary logic circuits require low contact resistance (R_C) in two-dimensional (2D) field-effect transistors (FETs).
• Achieving low R_C in p-type 2D FETs is challenging due to significant Schottky barriers for hole injection, unlike their n-type counterparts.

Purpose of the Study:

• To reduce R_C in p-type monolayer WSe2 FETs to the sub-kΩ·μm range.
• To engineer both the contact and channel regions for efficient hole injection.
• To narrow the performance gap between n-type and p-type 2D transistors.

Main Methods:

• Utilized degenerately Ta-doped multilayer MoSe2 as a p-type contact material laminated onto MOCVD-grown WSe2 channels.
• Employed a postfabrication NO anneal for selective channel doping via NO chemisorption at Se-vacancy sites.
• Combined complementary doping with a clean 2D/2D van der Waals (vdW) interface.

Main Results:

• Achieved R_C in the sub-kΩ·μm range for p-type monolayer WSe2 FETs.
• Demonstrated efficient hole injection, leading to high ON-current (I_ON) values up to 53 μA/μm.
• Preserved the contact properties of the Ta-doped MoSe2 while doping the WSe2 channel.

Conclusions:

• The presented strategy successfully reduces R_C in p-type 2D FETs by combining contact and channel engineering.
• This approach significantly advances the development of complementary 2D logic technologies.
• The method provides a pathway for balanced performance in n-type and p-type 2D transistors.