Dielectric measurements on oxidized and hydrogenated chemical vapor deposited diamond films

Abstract

The influence of oxidation, hydrogenation, and annealing on the dielectric properties of microwave plasma enhanced chemical vapor deposited diamond films was measured in the 45 MHz-20 GHz range using an open-ended coaxial probe. A dielectric response was detected around 10(8)-10(9) Hz for the hydrogenated samples, in contrast to the oxidized films, which showed no response in that frequency range. The amplitude and position of the detected response were clearly dependent on the sample quality and the state of the surface. Fitting of the experimental data to the Cole-Cole expression for dielectric relaxation showed a near-Debye behavior of the dielectric permittivity. We propose that the dielectric response is a result of two-dimensional plasmons, corresponding with a hole concentration of similar to10(13) cm(-2) at the diamond surface, induced by the hydrogen termination. Analogous to the well-known hydrogen-induced surface conductivity, the dielectric signal disappeared after annealing the diamond films at 200 degreesC. (C) 2002 American Institute of Physics.