Regensburg 2010 – scientific programme

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DS: Fachverband Dünne Schichten

DS 14: Thermoelectric Thin Films and Nanostructures II

DS 14.3: Talk

Tuesday, March 23, 2010, 14:45–15:00, H8

Thermal Conductivity Of Single Crystalline SiGe/Si Multilayers Below The Amorphous Limit — •Armando Rastelli, Fabio Pezzoli, Peixuan Chen, Mathieu Stoffel, and Oliver G. Schmidt — Institut für Integrative Nanowissenschaften, IFW Dresden, Helmholtzstr. 20, 01069 Dresden

We report on the fabrication, structural properties and cross-plane thermal conductivity measurements of multilayers of epitaxial SiGe self-assembled nanodots in Si matrix. Thermal conductivity measurements are performed with the differential 3-omega method using metal strips on top thin (30 nm thick) dielectric layers deposited by atomic layer deposition. With this approach we are able to reliably determine the cross-plane thermal conductivity of semiconductor layers as thin as 30 nm. Moreover we present a new method for error evaluation, which, based on Monte Carlo simulation, takes into account the uncertainties of all parameters entering in the model equations used to determine the thermal conductivity. The study reveals a rather linear dependence of the thermal conductivity on the SiGe interlayer spacing. For the thinnest Si-spacer thickness available (3 nm), our single-crystalline SiGe structure shows thermal conductivity values well below those of amorphous Si. Finally we discuss the results and possible routes to further reduce the thermal conductivity.