In situ Raman monitoring of the growth of diamond films in plasma-assisted CVD reactors

A set-up designed for the Raman characterization of a diamond film during its growth in different plasma CVD reactors is described. It is composed of a pulsed laser and a gateable detector in order to synchronize the Raman detection with the pulses of the laser. The optical components are designed for working in the visible and near UV. The installation is specially designed for a remote detection and can be used in industrial reactors as well as in laboratory experiments. The detectivity of the set-up is analysed through some typical diamond spectra and it is shown that it is of the same order of what is obtained with a micro-Raman multichannel spectrometer equipped with a continuous laser. Some results are reported; it is shown how this set-up may be used to control in real time the deposition process.