Influence of Interface Thermal Conductance on the Apparent Thermal Conductivity of Thin Films

The thermal conductance of 8- to 200-nm-thick films of SiO and MgO is measured in the 2 temperature range 78 - 400 K using the 3 omega method. The apparent thermal conductivity of the films is reduced by the finite thermal conductance of the interfaces between the metal film heater and the dielectric layer, and between the dielectric layer and the Si substrate. For SiO films at 250 K, the conductance of the two interfaces added in series is G 6 10 3 2 I W cm 2 K, equivalent to the thermal conductance of a 20-nm-thick film of SiO . For MgO 2 films, G is significantly smaller, G 2.5 10 3 W cm 2 K. I I