Thermal transport in phononic crystals and the observation of coherent phonon scattering at room temperature

Seyedhamidreza Alaie; Drew F Goettler; Mehmet Su; Zayd C Leseman; Charles M Reinke; Ihab El-Kady

doi:10.1038/ncomms8228

Thermal transport in phononic crystals and the observation of coherent phonon scattering at room temperature

Nat Commun. 2015 Jun 24:6:7228. doi: 10.1038/ncomms8228.

Authors

Seyedhamidreza Alaie¹, Drew F Goettler², Mehmet Su², Zayd C Leseman³, Charles M Reinke⁴, Ihab El-Kady⁵

Affiliations

¹ 1] Department of Mechanical Engineering, University of New Mexico, Albuquerque, New Mexico 87131, USA [2] Manufacturing Training and Technology Center, University of New Mexico, Albuquerque, New Mexico 87131, USA [3] Deptartment of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico 87131, USA.
² 1] Department of Mechanical Engineering, University of New Mexico, Albuquerque, New Mexico 87131, USA [2] Manufacturing Training and Technology Center, University of New Mexico, Albuquerque, New Mexico 87131, USA.
³ 1] Department of Mechanical Engineering, University of New Mexico, Albuquerque, New Mexico 87131, USA [2] Manufacturing Training and Technology Center, University of New Mexico, Albuquerque, New Mexico 87131, USA [3] Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, New Mexico 87131, USA [4] Deptartment of Applied Photonic Microsystems, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.
⁴ 1] Department of Mechanical Engineering, University of New Mexico, Albuquerque, New Mexico 87131, USA [2] Deptartment of Applied Photonic Microsystems, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.
⁵ 1] Department of Mechanical Engineering, University of New Mexico, Albuquerque, New Mexico 87131, USA [2] Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, New Mexico 87131, USA [3] Deptartment of Applied Photonic Microsystems, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.

PMID: 26105560
DOI: 10.1038/ncomms8228

Abstract

Large reductions in the thermal conductivity of thin silicon membranes have been demonstrated in various porous structures. However, the role of coherent boundary scattering in such structures has become a matter of some debate. Here we report on the first experimental observation of coherent phonon boundary scattering at room temperature in 2D phononic crystals formed by the introduction of air holes in a silicon matrix with minimum feature sizes >100 nm. To delaminate incoherent from coherent boundary scattering, phononic crystals with a fixed minimum feature size, differing only in unit cell geometry, were fabricated. A suspended island technique was used to measure the thermal conductivity. We introduce a hybrid thermal conductivity model that accounts for partially coherent and partially incoherent phonon boundary scattering. We observe excellent agreement between this model and experimental data, and the results suggest that significant room temperature coherent phonon boundary scattering occurs.