DC current and AC impedance measurements on boron-doped single crystalline diamond films

In this paper, we report the first measurement of impedance on boron-doped single crystalline diamond films from 0.1 Hz to 10 MHz with the temperature ranging from -100 degreesC up to 300 degreesC. The Cole-Cole (Z' via Z") plots are well fitted to a RC parallel circuit model and the equivalent Resistance and Capacitance for the diamond films have been estimated using the Zview curve fitting. The results show only one single semicircle response at each temperature measured. It was found that the resistance decreases from 70 GOmega at -100 degreesC to 5 kOmega at 300 degreesC. The linear curve fitting from -100 degreesC to 150 degreesC shows the sample has an activation energy of 0.37 eV, which is consistent with the theoretical value published of this kind of material. The equivalent capacitance is maintained at the level of pF up to 300 degreesC suggesting that no grain boundaries are being involved, as expected from a single crystal diamond. The activation energy from the dc current-temperature curves is 0.36 eV, which is consistent with the value from ac impedance. The potential of this under-used technique for diamond film analysis will be discussed. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.