Far infrared (THz) electromagnetic radiation represents a valuable probe for material characterization. Charges in materials will react to THz radiation, giving rise to absorption that can be used to determine their conductivity. A main limitation of electromagnetic radiation is that it cannot be focused below the diffraction limit, which sets a constrain to the spatial resolution of conductivity maps of materials. Being able to map the conductivity with high resolution over large areas can provide important information about material's imperfections, improve fabrication processes and enhance the performance of devices based on these materials. In this project, we have developed a novel instrument that can be used to determine the photo-conductivity of materials with a high spatial resolution (well below the diffraction limit) over large areas. This instrument can be used to map the quality of materials relevant for optoelectronic and energy applications, such as semiconductor thin films and graphene layers.
