Effect of non-homogeneity of Al/CVD diamond interfaces on AC properties

The capacitance and conductance of an Al/diamond interface was measured in the temperature range 231–334 K. The conductance and loss tangent curves presented two maxima. To explain these results, a simplified electrical equivalent circuit model was proposed that includes the electrical characteristics of the two phases of diamond. The equivalent circuit comprises the resistances and capacitances corresponding to depletion regions and the bulk for grains and grain boundaries, respectively. Simulation of the conductance and capacitance curves based on this model was used in theoretical analyses. Each curve maximum was associated with processes that occur in grains and grain boundary regions of polycrystalline diamond. Another more realistic model was also proposed, in which the capacitance and conductance of the equivalent circuit are described in terms of distribution functions.