Frequency-Dependent Conductivity in Polycrystalline Chemical Vapor Deposited Diamond Films

Studies have been made on frequency-dependent electrical conduction in polycrystalline diamond films prepared by plasma-enhanced chemical vapor deposition (PECVD). It is found by ac conductivity measurements that the electrical conduction in annealed diamond films is attributed to frequency-independent band conduction in a low-frequency range, f^0.8-dependent hopping conduction in a high-frequency range and thermal emission of carriers from trap levels. Activation energies of three trap levels are 0.62, 1.38 and 0.95 eV. The 0.62 and the 1.38 eV trap levels are passivated in hydrogenated diamond films.