Thermal conductivity of ultrathin tetrahedral amorphous carbon films

We investigate the thermal conductivity of ultrathin tetrahedral amorphous carbon (ta-C) films on silicon, down to subnanometer thickness. For films with an initial sp(3) content of 60%, the thermal conductivity reduces from 1.42 to 0.09 W/mK near room temperature as the thickness decreases from 18.5 to similar to 1 nm. The variation in ta-C film thickness is accompanied by changes in Young's modulus, density, and sp3 content. The thermal resistance of the finite-thickness interface layer, which forms between ta-C and silicon, is similar to 10(-8) m(2) K/W near room temperature, thus producing a noticeable effect on thermal transport in ultrathin ta-C films. (C) 2008 American Institute of Physics.