STRUCTURE AND DIELECTRIC CHARACTERIZATION OF A CHEMICALLY VAPOR-DEPOSITED DIAMOND THICK-FILM

The dielectric constant (epsilon) and the loss tangent (tan delta) of a chemically vapor deposited diamond thick film (435 mu m), determined by the a.c. impedance measurement technique, at temperatures (T) between 298 and 473 K and at frequencies (f) between 1 and 1000 kHz are reported. The film had a well-faceted crystalline morphology, single phase crystalline structure and minimal non-diamond carbon. In the temperature and the frequency range of study, the dielectric constant and the loss tangent can be expressed by the following equations. ln epsilon = 0.476ln(T)-0.0389 ln(f)-0.101 tan delta = 2.73 x 10(-4)(T)+5 x 10(-6)(f)-0.0443 The dielectric constant increases with temperature and decreases with frequency, while the loss tangent increases slightly with both temperature and frequency. The values measured are much larger than the corresponding values for natural diamond because of the polycrystalline nature and the presence of impurities in the film.