THE INFRARED PROPERTIES OF MAGNETRON-SPUTTERED DIAMOND-LIKE THIN-FILMS

We have measured the infrared reflectance, R, and the transmittance, T , of several amorphous and diamond-like carbon films deposited on GaAs substrates by d.c. magnetron sputtering in an Argon atmosphere. The t hickness, d, and the refractive index, n, were found from the fringes in the near-infrared reflectance, which were due to the interference i n the film, using an appropriate model for the absorption. The mid-inf rared absorption coefficient cu, obtained from 1-R-T, was then fitted to a model of the absorption involving both vibrations and electronic transitions, using d and n. The electronic absorption was found to dec rease with increasing pressure, along with an increase in the intensit y of the hydrogen vibrational features. We associate the transparency with the presence of hydrogen and present support for this view by mea suring a film in which hydrogen was deliberately introduced.