One-Dimensional Edge Contacts to a Monolayer Semiconductor

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Electrical contact integration is vital for van der Waals (vdW) heterostructures in electronics and optoelectronics.
• Scalable methods for accessing buried monolayer 2D semiconductors are currently lacking.

Purpose of the Study:

• To develop a scalable methodology for creating edge electrical contacts to hexagonal boron nitride (hBN) encapsulated monolayer molybdenum disulfide (MoS2).
• To evaluate the performance of these edge contacts in terms of contact resistance, carrier mobility, and current density.

Main Methods:

• Combination of reactive ion etching, in situ Ar+ sputtering, and annealing.
• Fabrication of edge contacts on hBN-encapsulated monolayer MoS2.

Main Results:

• Achieved relatively low edge contact resistance, comparable to top contacts.
• Demonstrated high carrier mobility (up to ~30 cm2 V-1 s-1) and on-current density (>50 μA/μm).
• Preserved intrinsic MoS2 channel quality, resulting in a steep subthreshold swing (116 mV/dec) and negligible hysteresis.

Conclusions:

• Edge contacts offer a viable and scalable solution for electrical access to encapsulated 2D semiconductors.
• This method is highly promising for large-scale implementation of vdW heterostructure devices, particularly those using air-sensitive materials.
• The ability to create arbitrarily narrow edge contacts facilitates further miniaturization of 2D electronic devices.