AC conductance and impedance spectroscopy of polycrystalline diamond films” Diamond Relat. Mater., 13 (2004) 89

Impedance measurements were performed in the frequency and temperature domain to infer the bulk and grain boundary transport of freestanding polycrystalline diamond films.Analyzed samples appear like insulators up to a threshold temperature where leaking becomes evident.Depending on deposition conditions and thickness, frequency independent conduction channels add to AC ones.The real component of conductivity, measured at different temperatures, can be reduced to a master curve according to a single hopping transport process.Ther efore, also the real and imaginary component of impedance, measured at different temperatures in the 2–10 7 Hz frequency range, can be reduced to a master curve and plotted vs.a reduced angular frequency showing a circuit structure more complex than a simple Voigt element.The Nyquist plot is formed by two different lobes that have been interpreted as related to grain and grain boundary dielectric contributions.However , only a single dielectric loss peak is achieved b