Influence of radio frequency power on thermal diffusivity of plasma enhanced chemical vapor deposition-grown hydrogenated amorphous carbon thin-films

Thermal diffusivity () of hydrogenated amorphous carbon (a-C:H) thin-films was characterized using the picosecond thermoreflectance measurement technique in the present study. The samples were fabricated in a plasma enhanced chemical vapor deposition system with varying radio frequency (RF) discharge powers from 15 to 70 W. Chemical bonding properties of the a-C:H films were determined from the Fourier transform infrared spectra and Raman spectroscopy. Results show that is enhanced from 0.07 to 0.20 mm² s^-1 as the RF power increases. It attributes to the dehydrogenation of film resulting from the bombardment of high-energy ion species that breaks C-H bonds at the lower power regime. Particularly at the highest RF power, however, the increase of is more influenced by the restructuring of bonding configuration associated with the breaking up of sp² clusters into smaller ones.