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).

DOI: 10.1063/1.5022097

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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