Thickness of the near-interface regions and central bulk ohmic resistivity in lead lanthanum zirconate titanate ferroelectric thin films

We have developed a method to separate the low-resistive near-interface regions (NIRs) from the high-resistive central bulk region (CBR) in a ferroelectric thin film. The NIR thickness and the CBR resistivity can thus be accurately determined. Using lanthanum-doped lead zirconate titanate films as an example, we show that the total thickness of the NIRs depends only on the electrode materials in use (Ir and Pt), while the CBR resistivity depends only on the impurity doping levels (La = 1.5% and 3%). The fact that the NIR is much narrower when Pt electrodes are used instead of Ir, and that the NIR resistivity is always considerably lower than the central bulk, suggest that the NIRs is probably originated from material nonstoichiometry/defects rather than the band bending at metal/insulator interfaces. (C) 2002 American Institute of Physics. [DOI: 10.1063/1.1532548].