Shape customization of 2D materials using maskless ultrafast laser lithography

Abstract

Herein, maskless ultrafast laser lithography was demonstrated for the shape customization of two-dimensional nanomaterials. Precise etching along the ablation edges of graphene nanoflakes mounted onto a metal-coated silicon was achieved. By controlling the polarization direction (perpendicular to the scanning direction), residual tentacle-like structures were manipulated to be parallel to the scanning direction, thereby achieving smooth ablation edges. Since the absorption rate of the stacking structure was effectively enhanced by the metal coatings, the ablation threshold of the graphene nanoflakes on the metal-coated substrates was lower than that of graphene nanoflakes on dielectric-coated substrates. After non-thermal ultrafast laser processing, the ablated edges suggested the presence of a well-preserved carbon network structure, which was confirmed by the low I_D/I_G intensity within the interior region. The structural integrity of the nanoflakes was preserved after the transfer process using polydimethylsiloxane. Ultrafast laser-tailored graphene nanoflakes in various shapes, including rectangle, triangle and narrow ribbon (featured size: 3 μm), were employed to construct two-terminal micro-circuits, exhibiting authentic electrical properties of two-dimensional materials owing to the direct contact between the nanoflakes and electrodes. This ultrafast laser lithography approach represents a novel fabrication method for the precise shape customization of two-dimensional materials, which is promising for the development of high-performance micro/nano devices.