Thermal transport through thin films: Mirage technique measurements on aluminum/titanium multilayers

Thermal transport properties of multilayer thin films both normal and paral lel to the layers were measured. Al/Ti multilayer films 3 mu m thick, with individual layers systematically varied from 2.5 to 40 nm, were studied on Si substrates. Layers of Al and Ti were nominally equal in thickness, with actual composition determined for each specimen using energy dispersive spe ctroscopy. The thermal diffusivity both in the plane and normal to the plan e of the films (thermal conductivity divided by specific heat per volume) w as found to decrease significantly with decreasing bilayer thickness. Pure Ti and Al films as well as Cu films from 0.1 to 5 mu m thick were also stud ied. In-plane electrical conductances of the Al/Ti multilayers were also me asured.