Transient and AC electrical conductivity of potassium chloride and potassium bromide thin films

Abstract

The transient and AC electrical conduction in KCl and KBr thin films have been studied at room temperature between 0.4 and 2.0 V. The time in the transient study covered the range 10-5 s to 104 s following the application of a step voltage. The frequency range in the AC study was 1 Hz to 200 kHz. From the frequency dependence of the AC conductivity and the application of Fourier transforms a transient current is calculated numerically, which differs from the experimentally determined transient current. Taking into consideration the experimental fact that the systems studied respond linearly to harmonically varying voltages, the observed discrepancies between AC and transient electrical conductivities are attributed to different mechanisms. Specifically the AC conductivity is attributed to hopping anions, whereas the transient conductivity is due not only to hopping anions but also to the release of trapped electrons by overcoming the barrier of the trap (Poole-Frenkel effect) alone or assisted by tunnelling through the barrier.