CAREER: Advanced Optical and Electrical Characterization of Novel Van der Waals Heterostructure Materials

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Nontechnical Description: With the development of nanotechnology and the shrinkage of device size, local optical and electrical properties are getting increasingly important in dictating the material functionalities, especially for the new class of material that are formed by stacking of material components of extremely small size in different shapes, often called nanotubes, nanowires, or dots. Their electrical and optical properties are sensitive to local imperfections such as impurities and defects. Conventional optical spectroscopy techniques face the difficulty in performing optical spectroscopy imaging with nanometer resolution. The research component of this CAREER award is focused on development of high-intensity, white-light source integrated with a scanning optical microscope to enable full-color imaging of nanoscale surface features. The small size of the light source and its fast decline in intensity over distance enable measurements with high resolution, high intensity and high signal to noise recording for exploring optical and electrical properties of various nanostructured materials. The project aims to integrate research components with various education and outreach activities with graduate and undergraduate students. The University of California at Riverside is a minority serving institution with large Hispanic student population and this project targets at increasing the participation of women and underrepresented minorities. Technical Description: Near-field scanning optical microscopy (NSOM) has been a powerful tool to break the diffraction limit of light for super-resolution images. This project aims to develop a new high-transmittance broad-bandwidth probe for a novel full-color NSOM, and to use it for investigation of the local optical and electrical properties of van der Waals (vdW) materials and heterostructure materials at the nanoscale. The research comprises a combination of vdW heterostructure fabrication, atomic-force-microscopy-integrated NSOM, scanning-tunneling-microscopy-integrated NSOM, and electrical transport measurements. By using this advanced optical characterization tool the research aims to elucidate: (i) the modified light-matter interaction in extremely confined systems; (ii) the optical and electrical properties of two-dimensional heterostructures, such as behavior of localized excitons or trions in graphene-MoS2 heterostructures; (iii) the electrical coupling between plasmonic mono-disperse clusters and graphene monolayer; and (iii) the band structure distributions in individual single-walled carbon nanotubes. The research components are integrated with various education and outreach activities with graduate, undergraduate and high school students, involving students from underrepresented minority groups.