Atomic-thin two-dimensional (2D) materials exhibit many unique and extraordinary properties such as excellent mechanical flexibility, good optical transparency, high thermal conductivity, and diverse electronic properties. Owing to all these characteristics, 2D materials have been extensively investigated as emerging materials for various fields, including electronics, nanophotonics, biology, and energy harvesting. Among most of these applications, it is essential to obtain desired micro/nano-scale patterns. The current lithographical methods such as electron beam lithography demonstrate the capability of high-resolution patterning, however, they usually require high cost and multi-step processing with complex capital instruments. Recently, researchers have developed direct laser ablation to achieve 2D materials patterning. Yet, the use of high-power ultrafast lasers is needed.
Herein, we report plasmon-enhanced optothermal nanoscissors (OTNS) to directly pattern 2D materials with a low-cost continuous-wave (CW) laser on a plasmonic substrate. The plasmonic substrate consists of a thin layer of quasi-continuous gold nanoislands (AuNIs). The plasmon-enhanced photothermal effect generates abundant highly localized heat, enabling rapid and precise ablation of 2D materials at any specific locations. By translating the sample stage or scanning the laser beam, desired patterns of 2D materials can be created.
OTNS can fabricate complex and arbitrary patterns on 2D materials with low power and high resolution down to ~300 nm. The feature size can be precisely controlled within a wide range from 300 nm to micrometer scale. Various periodic nanostructures were successfully patterned on graphene and MoS2, such as nanoribbons, nanodisk array, and nanohole array, proving the great reproducibility of OTNS. We further show OTNS can be used for fabricating complex patterns with arbitrary sizes and shapes. The results also demonstrate the defining strength of OTNS, where small feature < 1 μm can be realized. With the low-power operation, tunable feature size, and versatile patterning capabilities, OTNS offers the possibility to scale up the fabrication of 2D-material nanostructures for many applications such as biosensing and infrared photonic systems.