LATTICE DYNAMICS STUDY OF ANISOTROPIC HEAT CONDUCTION IN SUPERLATTICES

Past studies suggest that phonon confinement and the associated group velocity reduction are the causes of the observed drop in the cross-plane thermal conductivity of semiconductor superlattices. In this work, we investigate the contribution of phonon confinement to the in-plane thermal conductivit...

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Bibliographic Details
Published inMicroscale thermophysical engineering Vol. 5; no. 2; pp. 107 - 116
Main Author Chen, Bao Yang, Gang
Format Journal Article
LanguageEnglish
Published London Informa UK Ltd 22.04.2001
Taylor & Francis
Subjects
Condensed matter: structure, mechanical and thermal properties
Exact sciences and technology
Low-dimensional structures (superlattices, quantum well structures, multilayers): structure, and nonelectronic properties
Physics
Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties)
Aluminium arsenides
Confinement
Gallium arsenides
Inorganic compounds
Semiconductor materials
Dispersion relations
Quantum wells
Phonons
Theoretical study
Binary compounds
Equations of motion
Group velocity
Anisotropy
Lattice dynamics
Superlattices
Thermal conductivity
Germanium
Silicon
Lattice thermal conductivity
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Summary:Past studies suggest that phonon confinement and the associated group velocity reduction are the causes of the observed drop in the cross-plane thermal conductivity of semiconductor superlattices. In this work, we investigate the contribution of phonon confinement to the in-plane thermal conductivity of superlattices and the anisotropic effects of phonon confinement on the thermal conductivity in different directions, using a lattice dynamics model. The dispersion relation in a free-standing quantum well is calculated and compared with superlattices. We find that the reduced phonon group velocity due to phonon confinement may account for the dramatic reduction in the cross-plane thermal conductivity in superlattices, but the in-plane thermal conductivity drop, caused by the reduced group velocity, is small and cannot explain the reported experimental results. This suggests that the reduced relaxation time due to diffuse interface phonon scattering, dislocation scattering, etc., should make a major contribution to the in-plane thermal conductivity reduction in superlattices.
ISSN:1089-3954
1091-7640
DOI:10.1080/108939501750397454