LATERAL THERMAL-DIFFUSIVITY OF EPITAXIAL DIAMOND FILMS

Highly oriented heteroepitaxial diamond films grown on silicon (001) s ubstrates were investigated by photothermal displacement spectroscopy at transient thermal gratings. Lateral thermal diffusivities were meas ured as a function of the height within the 90 mum thick films. A stro ng diffusivity variation was observed from less than 1 cm2 s-1 near th e substrate interface up to 10 cm2 s-1 in the top growth region, which is about 80% of that for single-crystal type IIa diamond. The results are compared with those obtained from fibre-textured diamond films. T he structural properties are characterized using micro-Raman spectrosc opy.