Engineering the Modal Shape of Graphene Nanoelectromechanical Systems Using Focused Ion Beam Milling

Graphene nanoelectromechanical (NEMS) systems offer great promise for ultrasensitive force, mass, and pressure sensors due to their extremely low mass and electronic integrability. Crucial to these applications is the ability to tune the shape of the mechanical modes and their corresponding resonance frequencies. Here, we show that Focused Ion Beam (FIB) milling is a high-yield means to engineer the shape of graphene NEMS, which in turn modifies their mode shape. We describe the specialized cutting methods necessary to achieve complex geometries such as beams, tapered beams, and trampolines. We transduce the mode shapes using optical interferometry and show that they are consistent with membrane theory. This work is an enabling step for future work which relies on well-defined mode shapes, such as point mass-sensing.