Theoretical Study of the Ultralow Thermal Conductivity of Weakly-Bonded Germanium Quantum Dot Arrays in Silicon

概要

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Three-dimensional Ge quantum dot arrays in Si show an extreme thermal conductivity reduction. Two decrease effects are indeed obtained from a molecular supercrystal model. First, low phonon group velocities are computed by lattice dynamics. Second, near-field scattering is exalted assuming weak interface bonding. This prediction can lead to a significant increase of the thermoelectric figure of merit $\mathit{ZT}$ (inversely proportional to the thermal conductivity). For a broad temperature range from $\pm 300$ to 1200 K, Si--Ge supercrystals are modeled with various size parameters and present thermal conductivities equal or lower than that of air ($\pm 0.025$ W m-1 K-1 at 300 K).
2011-01-25