Photoluminescence patterns via single-layer exfoliation in Gr/MoS₂ heterostructure using contact-mode atomic force microscopy

The stacking of two-dimensional (2D) materials presents numerous opportunities for various nanodevice applications. Achieving atomic-thick precision in microscopic patterning is crucial to manipulating the functionalities and interfacial interactions of the 2D heterostructures. In this study, a silicon atomic force microscopy (AFM) tip was utilized to rub the surface of graphene (Gr)/MoS₂ heterostructure and manipulate its physical properties. The contact force between the AFM tip and Gr/MoS₂ surface was adjusted between 110 and 660 nN. Before rubbing, the photoluminescence (PL) intensity of MoS₂ was quenched due to the presence of Gr. After rubbing, the optical image and Raman spectroscopy acquired from the Gr/MoS₂ heterostructure indicated that Gr started to be exfoliated by a contact force exceeding 220 nN. The absence of Gr due to exfoliation led to the restoration of MoS₂′s pristine PL intensity. For demonstration, the AFM tip was used to exfoliate a designed micro-area covered with Gr using a 660 nN force, forming a patterned PL of MoS₂. This technique enabled the creation of different structures to develop unique multilayer 2D material devices.