Ultra-low thermal conductivity and acoustic dynamics of Si nanostructured metalattices probed using ultrafast high harmonic beams

¹ Department of Physics and JILA, University of Colorado and NIST, Boulder, CO, 80309, USA
² Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA
³ Materials Research Institute, Pennsylvania State University, University Park, PA 16802, USA
⁴ Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802, USA
⁵ Department of Electrical Engineering, Pennsylvania State University, University Park, PA, 16802, USA
⁶ Department of Physics, Pennsylvania State University, University Park, PA, 16802, USA
⁷ Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, 16802, USA

^* Corresponding author: begona.abadmayor@colorado.edu

Published online: 16 April 2019

Abstract

We extend optical nanometrology capabilities to smaller dimensions by using tabletop coherent extreme ultraviolet (EUV) beams. Specifically, we characterize thermal transport and acoustic wave propagation in 3D periodic silicon inverse metalattices with <15nm characteristic dimensions. Measurements of the thermal transport demonstrate that metalattices may significantly impede heat flow, making them promising candidates for thermoelectric applications. Extraction of the acoustic wave dispersion down to ~100nm shows good agreement with finite element predictions, confirming that these semiconductor metalattices were fabricated with a very high-quality. These results demonstrate that EUV nanometrology is capable of extracting both dispersion relations, and thermal properties of 3D complex nano-systems, with applications including informed design and process control of nanoscale devices.