Dielectric losses of self-supporting chemically vapour deposited diamond materials

Abstract The dielectric properties of microwave-assisted plasma chemical vapour deposition diamond are investigated over a wide frequency range. The dielectric losses of several grades of diamond from three different origins are measured from 1 kHz to 15 GHz by resonant methods. Very low losses were measured in some samples, but high losses were also found in similar grades. This gives rise to a great dispersion in the results, with dielectric loss values ranging from 10 −5 to 10 −1 . This shows that the dielectric loss is still an uncontrolled parameter in the commercially available diamond grades. A characterisation of the samples by X-ray photelectron spectroscopy and radioluminescence is also reported. The measured dielectric spectrum does not show a clear relationship with any of the parameters analysed.