Manipulating Nanopatterns on Two-Dimensional MoS2 Monolayers via Atomic Force Microscopy-Based Thermomechanical Nanolithography for Optoelectronic Device Fabrication

Atomically thin two-dimensional (2D) materials, such as monolayer molybdenum disulfide (MoS2), are candidate materials for future nanoelectronic and optoelectronic devices. However, implementation for some applications based on 2D materials strongly depends on fabricating functional nanostructures with specific shapes and sizes. This study reports a thermomechanical nanolithography technique for manipulating nanostructures on monolayer MoS2 using a heated atomic force microscope tip. Three types of nanopatterns, namely, the periodic spindle-shaped stick slip structure, periodic triangular stick-slip structure, and nanogrooves, were fabricated on monolayer MoS2 using the great tensile stress produced via thermomechanical cleaving of the flexible poly(methyl methacrylate) (PMMA) layer underneath the MoS2 layer. Several feature sizes were studied to accurately control the fabricated nanostructures. A friction force step was observed when the tip scratched from PMMA to MoS2 in the same scribing process because of the low frictional characteristics of MoS2, indicating that MoS2 can reduce the friction as compared to the tip that directly scratches on PMMA. The direct nanocutting technique of 2D materials proposed herein is a promising tool for manipulating nanopatterns on 2D materials for the future nanoelectronic and optoelectronic devices.