Current-characteristics and leakage-current of ferroelectric PLT thin films

Lead lanthanum titanate (PLT) thin films were prepared by MOD process. Current-time (I-t) curves at different voltages were measured at room temperature. Three different voltage ranges of low, intermediate and high field were divided according to current-time (I-t) curves. In low field range, the change of current with time can be simulated by attenuation of power index, and the attenuation coefficient intends to decline with the increase of the applied electric field. Under the intermediate field, the I-t curve started to horizontally fluctuate. Under the high field, the I-t curve fluctuates and the current rises with time. I-V curves were obtained by analysing the I-t curves of different regions. Simultaneously it was found that the zones of number of different electric fields were not the same when the samples had different formulas under the same process. Therefore the I-V curves were different. The theory of non-ohmic conduction can be explained by the models of space charge limited conduction (SCLC) and grain boundary limited conduction (GBLC). The theory of conduction was comparatively studied by the fields with different directions. Slow discharging process was observed after charging. The results are helpful in investigation of pyroelectric properties of the ferroelectric thin films.