Versatile Lithographic Technique for Generating Nanoscale Platelets for Levitation Experiments

We report progress on integrating two-dimensional (2D) materials into levitation systems using ion traps to enable substrate-free characterization. Materials such as graphene exhibit rich physical phenomena due to their unique lattice structures and properties. Conventional substrate-based measurement techniques, however, often introduce unwanted interactions, resulting in mixed or distorted signals. Levitation techniques eliminate substrate effects, allowing direct investigation of intrinsic material properties. In the initial stage, particle injection into the high-vacuum environment is conducted via electrospray, which requires suspensions containing billions of nanoparticles. A major challenge lies in transferring these atomically thin materials into the system without deformation or aggregation. To address this, we engineer submicron-sized platelets that support single layer graphene. The fabrication process, performed on commercial 4-inch SiO₂/Si wafers coated with graphene or Au film, involves multiple steps—micron-scale photolithography, Cr/Au liftoff to create a masking layer, ion milling of the mask, and SiO₂ selective etching or sonication—to produce a nanoplatelet suspension with a particle density of 2.5×10⁵/mm on wafers. Prototype platelets composed of gold are characterized using SEM imaging of electrosprayed particles and charge-to-mass (Q/M) measurements of trapped particles to verify their suitability for the system.