Heat conduction in alloy-based superlattices

Abstract

This work reports experimental studies of the thermal conductivity of alloy-based superlattices. Cross-plane thermal conductivity of a Si/Si0.71Ge0.29 (50 angstroms/10 angstroms) superlattice is measured based on the 3ω method. The measured thermal conductivity of this superlattice is 2-3 times smaller than that calculated from the Fourier heat conduction. This reduction in thermal conductivity is smaller than those observed in pure Si/Ge superlattices, possibly due to the smaller mismatch of the material properties between Si and Si0.71Ge0.29 as compared to between Si and Ge. To extend the 3ω method for measuring both the cross-plane and the in-plane thermal-conductivity of superlattices, a 2-wire 3ω method is developed. Preliminary experimental results are reported for a AlAs/Al0.62Ga0.38As (455 angstroms/410 angstroms) thick layer superlattice based on this method.