Ultrascaled Contacts to Monolayer MoS₂ Field Effect Transistors

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Two-dimensional (2D) semiconductors offer potential for advanced field-effect transistors (FETs) due to their electrostatic control.
• Scaling FETs requires reducing both channel length (L_CH) and contact length (L_C), but nanoscale contact scaling is challenging.

Purpose of the Study:

• To investigate the impact of scaling contact length (L_C) on the performance of monolayer molybdenum disulfide (MoS2) FETs.
• To evaluate current crowding effects at nanoscale contacts in 2D semiconductor FETs.

Main Methods:

• Fabrication and characterization of monolayer MoS2 FETs with varying channel lengths (down to 100 nm) and contact lengths (down to 20 nm).
• Electrical measurements to assess ON-current and other performance metrics.

Main Results:

• A significant reduction in ON-current (approximately 2.5x) was observed as contact length (L_C) scaled from 300 nm to 20 nm.
• Current crowding effects become pronounced at nanoscale contact dimensions, impacting device performance.

Conclusions:

• Contact scaling is a critical factor limiting FET performance in 2D materials.
• Accurate modeling of contact effects is essential for future nanoscale electronic devices, particularly beyond current silicon technology nodes.