Thermal conductivity measurement of amorphous Si/SiGe multilayer films by 3 omega method

The cross-plane thermal conductivities of five amorphous Si/Si0.75Ge0.25 multilayer films deposited by magnetron sputtering with period thicknesses ranging from 2.5 nm to 50 nm were investigated by a differential 3 omega method at room temperature. The measurement results demonstrate that the thermal conductivities of amorphous Si/Si0.75Ge0.25 multilayer films are independent of period thickness and are comparable to the corresponding result calculated according to the Fourier heat conduction theory using constituent materials' thermal conductivities. Structure disorder and sharp interfaces of multilayer films were confirmed by X-ray diffraction and scanning electron microscopy. The results indicate that in amorphous Si/Si0.75Ge0.25 multilayer system interface effects do not play a key factor to thermal transport at room temperature due to significant reduction of phonon mean free path induced by the structure disorder. (C) 2012 Elsevier Masson SAS. All rights reserved.