Leakage current-voltage characteristics of ferroelectric thin film capacitors

Tile depolarization current-poling voltage (J(D)-V) characteristics of ferr oelectric tilia films, such as Pb(Z(1-x)Ti(x))O-3 (x = 0.47, 0.70) (PZT) an d SrBi2Ta2O9 (SBT), have been investigated in order to interpret tile true leakage current-voltage (J(L)-V) characteristics of ferroelectric thin film s. We found that the contribution of the polarization current (J(P)) in non -switching polarization states, as well as the additional one arising mainl y from the partial switching polarization current; of PZT thin film capacit ors was essentially included in the charging current-voltage (J(C)-V) curve s measured by means of the conventional step-pulse method; as well as the s taircase method. Hence, we propose a new method fur measuring the leakage c urrent, called the 'reversed step-pulse' method; which can simultaneously d etermine both J(C)-V and J(D)-V at a given temperature. In addition, we pro posed a method for finding the J(L)-V curves by subtracting the J(P)-V curv es from the J(C)-V curves and discuss the true leakage conduction of PZT th in-film capacitors, which was determined to be due to a Poole-Frankel emiss ion rather than a Schottky emission.