Thermal properties of amorphous/crystalline silicon superlattices

A France-Lanord and S Merabia and T Albaret and D Lacroix and K Termentzidis, JOURNAL OF PHYSICS-CONDENSED MATTER, 26, 355801 (2014).

DOI: 10.1088/0953-8984/26/35/355801

Thermal transport properties of crystalline/amorphous silicon superlattices using molecular dynamics are investigated. We show that the cross-plane conductivity of the superlattices is very low and close to the conductivity of bulk amorphous silicon even for amorphous layers as thin as similar or equal to 6 angstrom. The cross-plane thermal conductivity weakly increases with temperature which is associated with a decrease of the Kapitza resistance with temperature at the crystalline/amorphous interface. This property is further investigated considering the spatial analysis of the phonon density of states in domains close to the interface. Interestingly, the crystalline/amorphous superlattices are shown to display large thermal anisotropy, according to the characteristic sizes of elaborated structures. These last results suggest that the thermal conductivity of crystalline/amorphous superlattices can be phonon engineered, providing new directions for nanostructured thermoelectrics and anisotropic materials in thermal transport.

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