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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

NECKING EFFECTS CONTROL THERMAL CONDUCTIVITY OF PHONONIC MEMBRANES

Get access (open in a dialog) DOI: 10.1615/IHTC16.nmt.023703
pages 7049-7053

Résumé

Use of thermoelectric devices in modern technology is limited by the lack of inexpensive materials with high electrical but low thermal conductivity. Recent studies demonstrated that arrays of holes could reduce thermal conductivity of thin silicon membranes, while keeping high electrical conductivity. Here, we use micro-TDTR experiments and Monte-Carlo simulations study how thermal conductivity of silicon membranes at room temperature is reduced by arrays of holes with different dimensions and lattice types. We demonstrate that the size of the passage between the holes – the neck – becomes the dominant factor that determines the thermal conductivity of phononic membranes, regardless of the lattice, period, or surface-to-volume ratio. Moreover, we found that necks narrower than 60 nm could create directional heat fluxes in the passages between the holes. We conclude that the neck may not only determine the thermal conductivity of phononic nanostructures but may even control the heat conduction regime in the passages between the holes. Thus, the neck is the parameter that holds the key to the optimization of thermoelectric efficiency of phononic membranes.