RELATION BETWEEN THE HFCVD DIAMOND GROWTH-RATE, THE LINEWIDTH OF RAMAN-SPECTRUM AND THE PARTICLE-SIZE

The microstructure of a thin diamond film determines its functionality and reliability. Thus, knowledge of the phenomena influencing the sta bilisation of a particular microstructure is widely requested. Here th e occurrence of a linear relation between the 1332 cm(-1) Raman line-w idth and the growth rate of HFCVD diamond thin film is shown. A linear dependence of the Raman line-width on the reciprocal of the diamond p article size, measured by X-ray diffraction, already substantiated for MWCVD thin films, is shown to exist also for HFCVD films. Consequentl y the average particle size and the film growth rate are also shown to be related. The phonon confinement model has been reconsidered and a new phonon diffusion model is proposed to explain these results. Accor ding to this model the phonon energy, initially confined in a particle , is allowed to diffuse into the matrix with time. Finally, it is prop osed that the relation of the film growth rate with the particle size is due to the concomitant effects of the matter diffusion process, nec essary to reach and stabilize crystalline order, and the film growth t hat mainly depends on process deposition conditions.