Tem Characterisation of Electrolytic Separated Specimens of Strontium Bismuth Tantalate Ferroelectric Thin Films

Abstract

Preparation of specimens for Transmission Electron Microscopy usually involves elaborate and aggressive procedures that can produce artefacts in the observations. In this work we use an original preparation method for thin films that involves the electrolytic separation of the film from the substrate. Developed initially to study the characteristics of films isolated from the substrate, this method proves to be easier, less time consuming and in principle less intrusive than the traditional ones. The materials analysed are Strontium Bismuth Tantalate (SBT) ferroelectric films, processed by multiple deposition onto Pt/TiO 2 /SiO 2 substrates of sol-gel derived solutions and crystallisation by Rapid Thermal Processing (RTP) at 650°C. Final thickness range between 70 and 500 nm, which test the versatility of the method to obtain TEM specimens from films with varying thickness, and, at the same time, allows us to study the differences that the deposition of several layers may induce. Several issues concerning the optimisation of the SBT thin films processing need TEM analysis, and are also addressed in this work.