Grain size influence on admittance of diamond thin films

Abstract

Small amplitude AC characterization of diamond thin films of different thickness and grain size has been carried out. The frequency dependent admittance, measured as a function of temperature, has evidenced similar trends for samples grown by using different deposition techniques, even if peculiar relaxations processes were found at higher temperatures in diamond films with larger grain sizes: changes in relaxation times activation energies related to grain sizes were observed. An analysis of imaginary impedance and electric modulus spectra enabled grain boundary, bulk and any other phase contribution to be separated and identified by reference to an equivalent electric circuit with three Voigt elements. Dielectric relaxations were studied concerning behavior of real permittivity. © 2008 IOP Publishing Ltd.