Controlled Microscale Etching of Hexagonal Boron Nitride through Graphene-Enhanced Femtosecond Laser Irradiation

Laser etching is an advantageous technique for processing and patterning two-dimensional (2D) materials, contributing to a high speed, high spatial precision, and non-contact, contamination-free procedure. While continuous-wave and ultrafast laser processing have been extensively explored in graphene and transition metal dichalcogenides (TMDs), laser ablation of hexagonal boron nitride (hBN) remains challenging due to hBN’s large bandgap and extremely low sub-bandgap. Here, we report a graphene-assisted femtosecond laser etching method that enables efficient ablation of hBN via enhanced laser absorption in a graphene/hBN heterostructure. The graphene layer effectively promotes absorbed laser energy transfer to the underlying hBN, facilitating localized material removal. Systematic studies reveal that a graphene thickness of 7 nm achieves the most efficient etching. Moreover, the presence of oxygen further improves the etching efficiency, indicating a photothermal–oxidative contribution. This technique offers a controllable route for fabricating hBN-based photonic, quantum, and nanomechanical structures. Examples of these applications will be demonstrated to illustrate the versatility of the graphene-assisted laser etching approach.