Leakage currents in thin ferroelectric films

The basic mechanisms of leakage current components of thin lead zirconate titanate (PZT) ferroelectric films grown by the sol-gel method have been studied. Characteristic regions of current-voltage characteristics with different charge transport mechanisms have been determined. It has been shown that there is an intermediate region which separates such regions. In one of them, the leakage current depends on properties of the contact of electrodes with PZT film at low voltages; in the other, the leakage current is controlled by intrinsic properties of the PZT film bulk, and the basic mechanism of charge transport is Poole-Frenkel emission. In the intermediate region, a stepwise change in the current has been observed, which is caused by relaxing breakdown of the Schottky barrier. Time dependences of the leakage currents have been determined. It has been shown that the leakage current decreases with increasing delay time before the Schottky barrier breakdown, and the dependence becomes opposite in character after the breakdown.