The microstructure of a thin diamond film determines its functionality and reliability. Thus, knowledge of the phenomena influencing the stabilisation of a particular microstructure is widely requested. Here the occurrence of a linear relation between the 1332 cm-1 Raman line-width 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 particle size, measured by X-ray diffraction, already substantiated for MWCVD thin films, is shown to exist also for HFCVD films. Consequently 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. According to this model the phonon energy, initially confined in a particle, is allowed to diffuse into the matrix with time. Finally, it is proposed that the relation of the film growth rate with the particle size is due to the concomitant effects of the matter diffusion process, necessary to reach and stabilize crystalline order, and the film growth that mainly depends on process deposition conditions.
RELATION BETWEEN THE HFCVD DIAMOND GROWTH-RATE, THE LINEWIDTH OF RAMAN-SPECTRUM AND THE PARTICLE-SIZE
1995
Abstract
The microstructure of a thin diamond film determines its functionality and reliability. Thus, knowledge of the phenomena influencing the stabilisation of a particular microstructure is widely requested. Here the occurrence of a linear relation between the 1332 cm-1 Raman line-width 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 particle size, measured by X-ray diffraction, already substantiated for MWCVD thin films, is shown to exist also for HFCVD films. Consequently 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. According to this model the phonon energy, initially confined in a particle, is allowed to diffuse into the matrix with time. Finally, it is proposed that the relation of the film growth rate with the particle size is due to the concomitant effects of the matter diffusion process, necessary to reach and stabilize crystalline order, and the film growth that mainly depends on process deposition conditions.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
