Abstract
We investigated strain and grain size effects on the thermal transport of nanocrystalline bismuth antimony telluride thin films using both experimental studies and modeling. The fabricated thin films exhibited the average grain sizes of 30 < d < 100 nm, and the strain of-0.8% < ε < -1.4% in the c-axis direction whereas that of a-b-axis direction was constant at 1.7%. The thermal conductivities were measured using a 3ω method at room temperature. We calculated the lattice thermal conductivity using a simplified phonon transport model that accounts for the strain effect based on Christoffel equation and Lennard-Jones potential, and the grain size effect based on the full distribution of mean free paths. The theoretical calculation was largely in good agreement with our experimental results, and the detailed results will be discussed in the Symposium.
