Ultrashort vertical-channel MoS₂ transistor using a self-aligned contact

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Two-dimensional (2D) semiconductors offer potential for ultra-scaled transistors.
• Scaling challenges exist for simultaneously reducing gate and channel lengths in short-gate transistors, often due to contact misalignment.
• Molybdenum disulfide (MoS2) transistors have demonstrated short gate lengths, but channel length scaling remains difficult.

Purpose of the Study:

• To develop a self-alignment process for fabricating ultra-scaled 2D transistors.
• To overcome processing difficulties in aligning source-drain contacts with gate electrodes.
• To achieve simultaneous scaling of both gate and channel lengths in MoS2 transistors.

Main Methods:

• Mechanical folding of graphene/BN/MoS2 heterostructures.
• Utilizing the heterostructure thickness to define channel length.
• Precise alignment of source-drain metals around the folded edge.

Main Results:

• Realization of sub-1 nm gate length and sub-50 nm channel length in vertical MoS2 transistors simultaneously.
• Achieved an on-off ratio exceeding 10^5.
• Demonstrated an on-state current of 250 μA/μm at 4V bias, a 40-fold improvement over non-self-aligned devices.

Conclusions:

• The developed self-alignment process is effective for fabricating ultra-scaled 2D transistors.
• This technique enables simultaneous gate and channel length scaling, crucial for next-generation electronics.
• Self-aligned MoS2 transistors exhibit significantly enhanced performance metrics.