Novel Behaviors in Low-Dimensional Materials and Heterostructures
MIE Department Seminar
March 1, 2016
11:00 AM - 12:00 PM
Novel Behaviors in Low-Dimensional Materials and Heterostructures
Lincoln J. Lauhon, PhD.
Department of Materials Science and Engineering, Northwestern University
Abstract: Low-dimensional materials enable the creation of new classes of devices with novel functionality arising from their geometries (e.g. 1-D nanowire core-shell heterostructures) and unique materials combinations (e.g. 2-D van de Waals heterostructures). However, there remain significant gaps in understanding of the origins of device behaviors. While 2-D materials beyond graphene are becoming “clean” enough to explore mesoscopic transport phenomena, the influence of dopants and defects on the intrinsic properties of 2-D materials is just beginning to be explored. In nanoscale heterojunction devices, extrinsic influences are very strong due to the extreme thinness. Our group undertakes correlated characterization of nanoscale structure and properties to understand intrinsic and extrinsic influences on the behavior of electrons, photons, and phonons at heterojunctions in the low dimensional limit. A change in thickness of only a monolayer, for example, has a profound influence on the behavior of 2-D heterojunctions,[1] presenting the significant challenge of connecting atomic scale electronic structure to microscale device behavior. We also find that point defects have sometimes counterintuitive influences on electronic properties,[2] and that combinations of point and line defects can be exploited to produce a new class of device that might be used for neuromorphic computing.[3] Finally, the extreme thinness enables access to new regimes of materials response.[4] The talk will identify challenges in material science that are motivated by the interest in exploring new physics and exploiting novel behaviors in devices.
[1] S. L. Howell et al. "Investigation of Band-Offsets at Monolayer–Multilayer MoS2 Junctions by Scanning Photocurrent Microscopy" Nano Letters 15, 2278 (2015); [2] I. S. Kim, et al. "Influence of Stoichiometry on the Optical and Electrical Properties of Chemical Vapor Deposition Derived MoS2" ACS Nano 8, 10551 (2014); [3] V. K. Sangwan et al. "Gate-tunable memristive phenomena mediated by grain boundaries in single-layer MoS2" Nature Nanotechnology 10, 403 (2015); [4] Chang-Hua Liu et al. "Optical control of mechanical mode-coupling within a MoS2 resonator in the strong-coupling regime" Nano Letters 15, 6727 (2015).
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.
Date posted
Oct 14, 2021
Date updated
Oct 15, 2021