Electrical behavior of Pb0.95La0.05Zr0.54Ti0.46O3 thin film based capacitors: Influence of space charge region

Abstract

We investigated the influence of space charge region (SCR) on the electrical properties of Pb0.95La0.05Zr0.54Ti0.46O3 (PLZT) thin film based capacitor structures. The metal/PLZT/Pt capacitors were prepared by using metal electrodes (Pt, Au, Al) of varying work function as top electrodes, and Pt as a bottom electrode. The SCR formed at the top interface between the PLZT film and the metal differs from each other in three capacitor structures. The results obtained from the hysteresis, dielectric, and leakage current measurements were analyzed to understand the variation in the electrical properties of the capacitors arising from the different SCRs formed at the interfaces. Among the three, the Pt/PLZT/Pt capacitor showed highest polarization and permittivity, and lowest FCC and coercive field. The Al/PLZT/Pt capacitor showed lowest polarization and permittivity, but higher coercive field and FCC. The leakage current increased with a decrease in work function of the top electrode. The Schottky conduction mechanism was found to be dominant in all the three capacitors. Both the photovoltaic parameters (short circuit photocurrent denisty and open circuit photovoltage) increased with the increase in work function of the top electrodes. These studies suggest the existence of wider SCR and higher space charge field at the top interface in the case of capacitor designed with an Al (or Au) top electrode as compared to the capacitor designed with a Pt top electrode.