Thermal conductivity of sputtered oxide films.

The thermal conductivity of oxide thin films deposited using dc, rf, and ion-beam sputtering is measured in the temperature range 80--400 K using the 3{omega} method. Thermal conductivity data for amorphous thin films of SiO{sub 2} are nearly identical to bulk {ital a}-SiO{sub 2}. Data for amorphous Al{sub 2}O{sub 3}, while having a magnitude and temperature dependence similar to bulk amorphous oxides, show a dependence on deposition method; rf sputtering of an Al{sub 2}O{sub 3} target produces films with a thermal conductivity 35% smaller than films prepared by ion-beam sputtering. Microcrystalline thin films show a rich variety of behavior: the conductivity of TiO{sub 2} films depends on the substrate tempreature {ital T}{sub {ital s}} and approaches the thermal conductivity of bulk TiO{sub 2} ceramics when {ital T}{sub {ital s}}{congruent}400 {degree}C; HfO{sub 2} films show glasslike thermal conductivity independent of annealing temperature up to 900 {degree}C; and MgO films display a crystalline thermal conductivity that is greatly reduced relative bulk values.