Thermal conductivity of ZrO [formula omitted] thin films

Abstract

The thermal conductivity of thin solid films may be considerably lower than bulk material ones. We have recently developed a new photothermal method which enables the determination of the thermal conductivity of the dielectric films, on various kind of substrates, with an accuracy better than 10 %. In this paper, we present the thermal conductivity of two kinds of ZrO 2 thin films (stabilized with Y 2O 3 or not). We observe that a decrease in the dielectric thickness leads to a drastic drop of the thermal conductivity λ a. The drop in the thermal conductivity has a similar shape for the two ZrO 2 phases. Phonons boundary scattering cannot contribute so significantly to the reduction of λ a. The most satisfactory explanation is that the thermal conductivity λ a is affected by an additional thermal resistance R, especially between ZrO 2 and alumina substrate. In the future, we intend to study in more detail the structures of the interfaces.