Low thermal conductivity of amorphous Si/Si0.75Ge0.25 multilayer films with Au-interlayers

The cross-plane thermal conductivity of amorphous Si/Si0.75Ge0.25 multilayer films with Au-interlayers prepared by magnetron sputtering was successfully measured using a differential technique at room temperature. Though gold has great thermal conductivity, the samples possess a thermal conductivity of 0.53 W/mK, which is about 50% of the amorphous Si/Si0.75Ge0.25 multilayer films. The interfacial thermal resistance is the sum of the phonon-phonon interfacial thermal resistance and the electron-phonon thermal resistance. The thermal conductivity of the samples are significantly determined by the electron-phonon coupling in a metal-nonmetal system and can be lower by choosing a convenient thickness of nonmetal and metal layers.