Altering thermal transport by strained-layer epitaxy
T Majdi and S Pal and A Hafreager and S Murad and RP Sahu and IK Puri, APPLIED PHYSICS LETTERS, 112, 194101 (2018).
Since strain changes the interatomic spacing of matter and alters electron and phonon dispersion, an applied strain can modify the thermal conductivity k of a material. We show how the strain induced by heteroepitaxy is a passive mechanism to change k in a thin film. Molecular dynamics simulations of the deposition and epitaxial growth of ZnTe thin films provide insights into the role of interfacial strain in the conductivity of a deposited film. ZnTe films grow strain-free on lattice-matched ZnTe substrates, but similar thin films grown on a lattice-mismatched CdTe substrate exhibit similar to 6% biaxial in-plane tensile strain and similar to 7% uniaxial out-of-plane compressive strain. In the T= 700K-1100K temperature range, the conductivities of strained ZnTe layers decrease to similar to 60% of their unstrained values. The resulting understanding of dk/dT shows that strain engineering can be used to alter the performance of a thermal rectifier and also provides a framework for enhancing thermoelectric devices. Published by AIP Publishing.
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