Frequency-Dependent Dielectric Breakdown in Thin Polyvinylcarbazole Films

Dielectric breakdown in thin polyvinylcarbazole (PVK) films prepared by vapor deposition polymerization has been investigated at various ac voltages. Real-time measurements were carried out automatically with a system composed of a digital oscilloscope, a controllable signal generator and a microcomputer. Self-healing breakdown takes place at the peak applied voltage. AC electric strength decreases with temperature, and increases with frequency in the range of 10 Hz–3 kHz. A gold electrode has a lower electric strength than an aluminum electrode. The frequency-dependent breakdown has been explained tentatively in terms of the field enhancement due to the hole space charge leading to carrier injection and resulting in the breakdown.