We present effective-medium calculations of the optical properties of chemical vapor deposition-grown diamond films, under the assumption that these films are contaminated by various kinds of defects. Two types of defective films are considered: (i) a distribution of graphite crystallites in diamond, with each crystallite small compared to the wavelength of light; and (ii) a rough diamond-air interface. The calculations are carried out by treating the film in case (i) and rough surface layer in case (ii) as homogeneous media with effective dielectric properties. In both cases, we find characteristic modifications of the frequency-dependent reflectivity. The experimentally observed reflectivity of a diamond film is very well reproduced by our calculation over a broad frequency range between 2 and 10 eV.

• Received 12 May 1994

DOI:https://doi.org/10.1103/PhysRevB.50.12073