Electrochemical Impedance Spectroscopy Studies of HF CVD Diamond Films

Diamond films were synthesized by a hot filament vapor deposition method using H₂/CH₄ gas mixtures. A Hioki impedance analyzer was used to study the dielectric properties of the deposited diamond films. The dielectric dispersion measurement yielded the real and imaginary parts of impedance of diamond films in the form of a Nyquist plot in a complex plane. The obtained results were fitted by using equivalent circuit which consists of three impedance (Z) components containing resistor R and capacitor C or constant phase element connected in parallel. The structure and quality of diamond films were analyzed by scanning electron microscopy and the Raman spectroscopy. The impedance measurements showed that concentration of non-diamond admixture has essential influence on electrochemical properties of diamond layers.