Realizing On/Off Ratios over 10⁴ for Sub-2 nm Vertical Transistors

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Ultrascaled transistors are crucial for next-generation electronics.
• Vertical transistors face challenges with off-state tunneling currents, limiting on/off ratios, especially in sub-5 nm channel lengths.
• Minimizing short-channel effects is essential for device performance.

Purpose of the Study:

• To suppress off-state tunneling current in vertical transistors.
• To enhance the on/off ratio of ultrascaled vertical transistors.
• To provide a general strategy for reducing short-channel effects.

Main Methods:

• Designing barrier height using van der Waals metal contacts.
• Laminating a Platinum (Pt) electrode onto a Molybdenum disulfide (MoS2) vertical transistor.
• Characterizing the metal/MoS2 interface and device performance.

Main Results:

• Achieved a high Schottky barrier by leveraging the work function difference between Pt and MoS2.
• Suppressed direct tunneling currents effectively.
• Realized record on/off ratios of 5 × 10^5 for 5 nm and 10^4 for 2 nm channel length vertical transistors.
• Demonstrated an optimized metal/MoS2 interface with minimal defects due to a low-energy lamination process.

Conclusions:

• Van der Waals metal contacts offer a viable route to enhance the performance of vertical transistors.
• The developed method significantly improves on/off ratios by mitigating tunneling currents.
• This approach provides a scalable solution for ultrascaled devices and reducing short-channel effects.