THERMAL-DIFFUSIVITY OF DIAMOND FILMS USING A LASER-PULSE TECHNIQUE

Polycrystalline diamond films were deposited using a microwave plasma-enhanced chemical vapor deposition process. A laser pulse technique was developed to measure the thermal diffusivity of diamond films deposited on a silicon substrate. The effective thermal diffusivity of a diamond film on silicon was measured by observing the phase and amplitude of the cyclic thermal waves generated by laser pulses. An analytical model is presented to calculate the effective in-plane (face-parallel) diffusivity of a two-layer system. The model is used to reduce the effective thermal diffusivity of the diamond/silicon sample to a value for the thermal diffusivity and conductivity of the diamond film. The average effective diffusivity values are 1.47 ± 0.03 and 1.83 ± 0.10 yielding thermal diffusivity values of 7.46 ± 0.90 and 7.33 ± 0.70 cm2/s, respectively, for the two samples; the calculated thermal conductivity values are 13.50 and 13.28 W/cmK, which are better than that of type la natural diamond. The phase and amplitude measurements give similar results. © 1990, The Electrochemical Society, Inc. All rights reserved.