CORRELATIONS BETWEEN RAMAN-SCATTERING AND THERMAL-EXPANSION BEHAVIOR FOR CVD AND NATURAL DIAMOND

To successfully use chemical vapour deposition (CVD) diamond thin film s in high temperature applications it is important to know their therm al expansion properties. The thermal expansion properties of natural s ingle crystalline diamond have been the subject of many studies. Howev er measuring these properties can be very difficult, especially for CV D diamond films due to the polycrystalline nature of these films. In t his article it is proposed to use Raman shift measurements to determin e the linear thermal expansion coefficient of diamond. A theoretical r elation, based on the Gruneisen basic definition, to correlate high te mperature Raman scattering data and linear thermal expansion data, wil l be derived. The verification of this relation, using literature data on Raman shifts and linear thermal expansion of natural diamond, is p resented. The results will be applied to a series of new Raman shift m easurements, obtained on flame and hot filament CVD diamond films, in the temperature range 20-600 degrees C.