J Mater Sci Technol ›› 2005, Vol. 21 ›› Issue (06): 879-882.

• Research Articles • Previous Articles     Next Articles

AC Impedance Behaviour of Black Diamond Films

Haitao YE,Olivier GAUDIN, Richard B.JACKMAN   

  1. Electronic and Electrical Engineering, University College London, Torrington Place, London WC1E 7JE, UK
  • Received:2005-07-20 Revised:1900-01-01 Online:2005-11-28 Published:2009-10-10
  • Contact: Haitao YE

Abstract: The first measurement of impedance on free-standing diamond films from 0.1 Hz to 10 MHz up to 300℃ were reported. A wide range of chemical vapour deposition (CVD) materials were investigated, but here we concentrate on `black' diamond grown by microwave plasma enhanced CVD (MWPECVD). 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 62 MΩ at room temperature to 4 kΩ at 300℃, with an activation energy around 0.51 eV. The equivalent capacitance is maintained at the level of 100 pF up to 300℃ suggesting that the diamond grain boundaries are dominating the conduction. At 400℃, the impedance at low frequencies shows a linear tail, which can be explained that the AC polarization of diamond/Au interface occurs.

Key words: Black diamond, Impedance spectroscopy, Activation energy