Effects of deposition time duration on thermal diffusivity of hydrogenated amorphous carbon films

In the present investigation we study the effects of film-deposition time duration on thermal diffusivity (α) of hydrogenated amorphous carbon (a-C:H) thin-films grown in a radio-frequency (RF) plasma enhanced chemical vapor deposition system. A set of films was deposited at 50W RF power for 40, 60, 80, and 100 min. Film characteristics were determined from the optical transmission spectroscopy, Fourier Transform Infrared spectroscopy, and Raman spectroscopy. Thermal diffusivity of a-C:H films was evaluated using the optical pump-and-probe technique on the aluminum-coated samples. Results show a trend of increase in - as the deposition time increases due to the microstructural changes associated with longer exposure to ion bombardment effects on the growth surface of the films.