Abstract:

Two-dimensional (2D) materials—graphene, hBN, and some clays—exhibit properties unattainable from their three-dimensional (3D) brethren. The differentiation derives primarily from alterations in the bandstructure and density of states (DOS) that emerge with loss of dimension. Effectively surfaces, the same 2D nature imbuing this promise also makes them acutely sensitive to the materials surrounding them. This sensitivity typically degrades performance and hence approaches most often attempt to minimize the interactions between a 2D-material and that of its surroundings. Here, an opposite tact is taken where these interactions are instead leveraged to enable functionality.

First, spectrally tunable infrared filters are created by altering graphene’s plasmonic dispersion using the dielectrics surrounding it resulting in gate-tunable variations of reflectance by over 1 μm. Subsequently, capacitive coupling between the substrate and the graphene is leveraged to realize a highly sensitive optical detector (>2,500 A/W) possessing the ability to integrate signal like a CCD while providing constant local read-out like a photodiode opening up new paradigms in sensing. Taken together, these
case studies highlight the utility of employing interlayer interactions for function in 2D-systems rather than considering them a parasitic source to be avoided.

Biography:

Thomas Beechem is a staff scientist in the Nanoscale Sciences Department at Sandia National Laboratories in Albuquerque, NM. In this role, Thomas leads efforts focused on elucidating, and then leveraging, thermal physics and the material responses of low-dimensional systems to enable next generation opto- and power electronics. He has authored over 60 archival publications and had his work selected as the featured “cover article” on 5 separate occasions by 4 different periodicals. He received a
2015 Defense Program Award of Excellence and was named one of Sandia’s “Up and Coming Innovators” in 2016. In 2017, he was named an associate editor of the Journal of Heat Transfer. Thomas has been at Sandia since 2009 where he began immediately after obtaining his doctorate from the Georgia Institute of Technology in Mechanical Engineering under Samuel Graham.

Pizza and discussion to follow!

BRING RESUMES!