Kelvin probe force microscopy study of SrBi2Ta2O9 and PbZr0.53Ti0.47O3 thin films for high-density nonvolatile storage devices

Abstract

Polycrystalline ferroelectric thin films of SrBi2Ta2O9 (SBT) and PbZr0.53Ti0.47O3 (PZT) were deposited on Pt/Ti/SiO2/Si substrate by pulsed laser deposition using an eclipse method and the surface potentials were observed by Kelvin probe force microscopy. The data suggest that the surface charge trap is a dominant effect over the ferroelectric polarization when a high electric field is applied on a cantilever during writing. This results from the increase of surface trapped charge and the saturation of ferroelectric remanent polarization. The data also indicate that the SBT thin films can easily trap surface charges than that of the PZT thin films. By properly biasing low voltage, the magnitude and the sign of surface potential are determined by the ferroelectric polarization than by the trapped surface charges.