van der Waals devices for surface-sensitive experiments

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Surface-sensitive characterization of van der Waals (vdW) devices is crucial for understanding phase transitions and electronic states.
• Integrating vdW materials into devices while preserving surface integrity for combined experiments remains a significant challenge.
• Conventional lithography methods often introduce surface contamination, hindering advanced spectroscopic analysis.

Purpose of the Study:

• To present a novel stencil lithography technique for fabricating vdW devices with pristine surfaces.
• To enable combined electrical transport and surface-sensitive measurements on vdW materials.
• To overcome limitations of conventional lithography in vdW device fabrication.

Main Methods:

• Resist-free stencil lithography using a shadow mask for patterning electrical contacts.
• Ultra-high vacuum (UHV) fabrication environment.
• Gold-assisted exfoliation for obtaining thin vdW flakes down to the single-layer regime.
• Fabrication of 1T-TaS2 devices for demonstration.

Main Results:

• Successful fabrication of micron-scale electrical contacts on vdW flakes.
• Demonstrated exfoliation of thin flakes down to the single-layer limit.
• Achieved reliable contacts for electrical pulsing and resistance measurements on 1T-TaS2 devices.
• Maintained clean surfaces suitable for angle-resolved photoemission spectroscopy (ARPES).

Conclusions:

• The stencil lithography approach provides a viable platform for fabricating vdW devices with high-quality surfaces.
• This method facilitates in-operando studies of vdW systems using surface-sensitive techniques.
• Enables detailed investigation of electronic properties and phase transitions in vdW materials within functional device architectures.