English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

The experimentally observed order-of-magnitude reduction in the thermalconductivity along the growth axis of (GaAs)_n/(AlAs)_n (or n x n)superlattices is investigated theoretically for (2x2), (3x3) and (6x6)structures using an accurate model of the lattice dynamics. The modification ofthe phonon dispersion relation due to the superlattice geometry leads toflattening of the phonon branches and hence to lower phonon velocities. Thiseffect is shown to account for a factor-of-three reduction in the thermalconductivity with respect to bulk GaAs along the growth direction; theremainder is attributable to a reduction in the phonon lifetime. Thedispersion-related reduction is relatively insensitive to temperature (100 < T< 300K) and n. The phonon lifetime reduction is largest for the (2x2)structures and consistent with greater interface scattering. The thermalconductivity reduction is shown to be appreciably more sensitive to GaAs/AlAsforce constant differences than to those associated with molecular masses.Comment: 5 figure

Phonon dispersion effects and the thermal conductivity reduction in GaAs/AlAs superlattices