Effect of structural features on the thermal conductivity of SiGe-based materials

KR Hahn and C Melis and L Colombo, EUROPEAN PHYSICAL JOURNAL B, 87, 150 (2014).

DOI: 10.1140/epjb/e2014-50239-5

Approach-to-equilibrium molecular dynamics have been utilized to investigate the thermal transport in SiGe-based materials focusing on the effect of structural changes while the chemical composition has been kept constant. At a Si:Ge ratio of 1:1, the thermal conductivity has been evaluated for crystalline SiGe with a periodic (ZnS-like) and random (alloy) distribution of Si and Ge atoms, for SiGe nanocomposite and for amorphous SiGe. Thermal conductivity has been found to be lowest in amorphous SiGe (0.9 W/mK). In the regime studied here, a non-linear behavior of 1/kappa to 1/L-z has been observed for amorphous SiGe, while a linear trend is found for all crystalline materials (ZnS-like, alloy and nanocomposite). This has been attributed to a wide spread in the mean free path of phonons dominating the thermal transport in the amorphous system.

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