MSE Colloquium: Lincoln Lauhon, Correlated Imaging of Low Dimensional Materials: Seeing and Understanding the Nanoscale

Professor and Associate Chair, Department of Materials Science and Engineering, Northwestern University

Abstract

Microscopy has played a central role in the advancement of nanoscience and nanotechnology by enabling the direct visualization of nanoscale structure, and by extension predictive models of novel physical behaviors. Correlated imaging of nanoscale structure and properties is an important frontier that can provide a rational basis for the discovery and application of new materials to meet challenges in energy, sustainability, medicine, and information technologies. I will describe our approach to correlated imaging with a focus on 1-D and 2-D semiconducting nanostructures in which the interaction between light and matter is strongly influenced by size, shape, and interfaces. Specifically, semiconductor nanowires are candidates to realize the next generation of efficient solid-state lighting and solar cells, and a fundamental understanding of their structure property relationships is essential to gauging and maximizing their potential. To understand how “bottom-up” semiconductor nanowires grow, and control their electrical properties, we have used atom probe tomography to visualize the distribution of atoms in three dimensions with nanoscale resolution, providing new insights into growth mechanisms and the resulting the distribution of dopant atoms. To better understand how nanowires convert light to electrical energy and vice versa, we have implemented scanning photocurrent microscopy (SPCM), in which energy conversion mechanisms are visualized by integrating spatial, spectral, and temporal resolution into scanned probe measurements of operating devices. We have recently extended SPCM to the analysis of 2-D materials as well. Our approach to characterization of model systems aims to identify applications that can truly benefit from the adoption of unconventional nanostructured materials.

Bio

Prof. Lauhon is a Professor and Associate Chair in the Department of Materials Science and Engineering at Northwestern University. He received a Ph.D. in Physics from Cornell with Wilson Ho (2000) and a B.S. in Physics from the University of Michigan (1993). Prior to joining Northwestern in 2003, he was a postdoctoral researcher in the Department of Chemistry and Chemical Biology at Harvard University with Charles Lieber. At Northwestern, the Lauhon group investigates novel structure-property relationships that arise in nanostructured materials with an emphasis on spatially resolved measurements. His work has been recognized with an NSF CAREER Award, a Sloan Fellowship in Chemistry, and a Camille Dreyfus Teacher Scholar Award.