Silver Nanowire-Based Near-Field Scanning Optical Microscope for Photocurrent Mapping

Silver-based Near-field Scanning Optical Microscopy provides access to high spatial resolution photocurrent image mapping of the surface of a variety of two-dimensional material and nanostructures. By observing the photocurrent from the interaction between nano-photons and nano-materials, nano-scale bandstructure information can be studied. For one of its application, strain-induced graphene wrinkle FET’s photocurrent has been investigated. Under different channel and gate bias voltages, the photocurrent responses have been mapped point by point, and bias-voltage-related bandstructure information has been obtained. 15 nm photocurrent imaging resolution has been achieved for the first time. Conventional scattering Near-field Scanning Optical Microscopy is not able to provide near-field electric field distribution within the gap between tip and sample. Here we provide an accurate method to reconstruct the near-field electric field on a wide range of two-dimensional material and nanostructures