Directly probing the carrier transfer length in 2D-material transistors

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional (2D) materials offer superior electrostatic gate control for transistors beyond the 1 nm logic technology node due to their thinness and defect-free surfaces.
• Scaling 2D transistors to channel lengths below 10 nm is a key goal for advanced electronic devices.
• The contact scaling limit for 2D transistors remains largely unknown due to the inability to directly probe carrier injection regions.

Purpose of the Study:

• To directly measure the carrier transfer length at the contact region of a 2D material transistor.
• To determine the scaling constraints for metal contacts in ultra-scaled 2D electronic devices.
• To provide critical data for the development of next-generation electronic devices.

Main Methods:

• Utilized cross-sectional scanning tunneling microscopy (STM) to directly probe the nanoscale contact region.
• Investigated a bismuth-contacted monolayer molybdenum disulfide (MoS2) transistor.
• Measured the carrier transfer length at the metal-semiconductor interface.

Main Results:

• The carrier transfer length was directly measured to be approximately 2.0 nm.
• This finding quantifies a critical parameter for contact scaling in 2D transistors.
• Established a method for probing carrier injection in nanoscale electronic devices.

Conclusions:

• The determined carrier transfer length of 2.0 nm provides essential information for contact scaling in 2D transistors.
• This research addresses a key unknown limiting factor for future ultra-scaled electronic devices.
• The employed cross-sectional STM technique enables direct measurement and understanding of carrier transport at contact interfaces.