Kate Murphy
Materials Scientist
ASEA Brown Boveri

Strain effects on thermal conductivity of nanostructured silicon by Raman piezothermography

Location: EB1 Room 1011

Friday, March 18th 2016 - 11:00 am

A fundamental problem facing the rational design of materials is the independent control of electrical and thermal properties, with implications for a wide range of applications including thermoelectrics, solar thermal power generation, and thermal logic. One means of tuning transport is elastic strain, which has long been exploited to improve carrier mobility in electronic devices. Nanowires are ideal for the study of strain effects due to the availability of a range of elastic strain an order of magnitude larger than in bulk. However, experimental measurements of strain-mediated thermal conductivity in nanowires have been limited due to the complexity of simultaneously applying and measuring stress or strain, heating, and measuring temperature.

In this talk, I will discuss a novel non-contact approach for measuring strain effects on thermal conductivity. We applied a uniaxial load to individual Si nanowires, Si thin films, and Si micromeshes under a confocal μ-Raman microscope and, using the Raman laser as a heat source and the Raman spectrum as a measure of temperature, determined thermal transport properties (conduction, convection, and contact resistance). The directions suggested by our experiments, as well as the development of the method, will allow for more robust understanding and control of thermal transport in nanostructures.

Finally, I will briefly discuss my current work in the materials group at ABB's US Corporate Research Center on Centennial Campus.

North Carolina State University