MEASUREMENT OF INTRINSIC THERMAL CONDUCTIVITY OF DLC AND THERMAL BOUNDARY RESISTANCE BY WIDE FREQUENCY 3ω METHOD
Interfaces dominate the thermal resistances in diamond-like carbon (DLC) film and aligned carbon nanotube (CNT) arrays. This paper uses 3ω thermometry extended to ~ MHz to separate interface and intrinsic resistances. The surface thermal impedance model of multilayer nano film in wide frequency domain is established. Based on the method of parameter sensitivity analysis, thermal conductivity of the film can be obtained directly at high frequency while thermal boundary resistance (TBR) of DLC/CNT is measured at medium and low frequency. For DLC/CNT/Si multilayer structure, the thermal conductivity of DLC and thermal boundary resistance of DLC/CNT are measured respectively at different temperatures. It shows that TBR between DLC/CNT array decreases as the temperature increases. The mechanism of the suppression may be explained by the physics of phonon waves interacting with rough surface morphologies. This temperature dependence is attributed to inelastic phonon scattering. Thermal conductivity of DLC increases with the increasing temperature and is predicted with minimum thermal conductivity approach. The temperature dependency of the effective thermal conductivity between 270 and 460 K is in good agreement with theoretical predictions.