Heat conduction in alloy-based superlattices

This work reports experimental studies of the thermal conductivity of alloy-based superlattices. Cross-plane thermal conductivity of a Si/Si_0.71Ge_0.29 (50 Å/10 Å) 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 Si_0.71Ge_0.29 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/Al_0.62Ga_0.38As (455 Å/410 Å) thick layer superlattice based on this method