Measuring thermal conductivity of CVD diamond and diamond-like films on silicon substrates by holographic interferometry

It is a great challenge to measure accurately the high values of thermal co nductivity of diamond and diamond-like materials in the form of thin films. The objective of this study is to develop a technique based on the princip le of holographic interferometry to determine these values relative to othe r well-known values of bulk materials such as aluminum, copper, or molybden um. Our approach in this work was to measure directly the effective thermal diffusivity of diamond film/silicon substrate samples by first observing t he change of the interference fringe pattern related to the deformation of the sample that was induced by a prescribed thermal excitation source. The thermal conductivity of diamond thin film was then determined from the know n values of diamond density and specific heat at constant pressure based on an analytical model of a two-layer structure system developed for this stu dy. In this paper, the efficacy of using this approach will be presented wi th a comprehensive result of the calculated thermal conductivity on a serie s of CVD diamond and diamond-like thin films on silicon substrate samples p repared by different CVD techniques including microwave CVD and hot-filamen t CVD. (C) 1999 Published by Elsevier Science S.A. All rights reserved.