Realization of Nanoscale Mapping of Noise Source Activities on Graphene Domains*

We report a “noise spectral imaging” strategy to directly map the noise source activities in graphene domains. Here, the lateral current and noise maps were measured by scanning a conductive contact probe on the graphene surface. The measured data were analyzed by using a two-dimensional network model to obtain the sheet resistance and charge trap density maps inside graphene domains, on domain boundaries, and on the edge of graphene. The results showed high activities of noise sources and large sheet resistance values at the domain boundary and edge of graphene. Furthermore, the top layer of double-layer graphene was found to have lower noises than those of single-layer graphene, as predicted previously. Our method allows one to image the localized noise source distribution in two-dimensional electronic channels such as graphene, and thus it can be a powerful tool for the basic research and applications about two-dimensional transports in nanostructures.