Spatial Mapping of Charge Puddles in CVD-Grown Graphene Using Photocurrent Responses from Patterned Gold Nanostructures

We present a novel technique for spatially mapping charge puddles in CVD-grown graphene using photocurrent measurements. By patterning gold nano-triangles onto the graphene, we exploit their C3 symmetry to probe directionally dependent electronic properties. Electrodes are positioned to collect currents in both the x and y directions, enabling the capture of anisotropic behaviors. Varying the polarization of an incident laser allows the nano-triangles to generate photocurrents in multiple directions, testing the isotropy of graphene's electronic response. Our results reveal how the spatially varying electronic environment, characterized by charge puddles, interacts with the patterned structures, providing new insights into graphene's spatially and current direction-dependent electronic behavior. This technique is a powerful tool for understanding spatial inhomogeneities in graphene and other two-dimensional materials.