Comparison of TEM specimen preparation of perovskite thin films by tripod polishing and conventional ion milling

In this article, the effects of the transmission electron microscopy (TEM) specimen preparation techniques, such as ion milling and tripod polishing on perovskite oxides for high-resolution TEM investigation, are compared. Conventional and liquid nitrogen cooled ion milling induce a new domain orientation in thin films of SrRuO3 and LaFeO3 grown on (001)-oriented SrTiO3 substrates. This is not observed in tripod-polished specimens. Different ion milling rates for thin films and substrates in cross-section specimens lead to artefacts in the interface region, degrading the specimen quality. This is illustrated by SrRuO3 and PbTiO3 thin films grown on (001)-oriented SrTiO3. By applying tripod polishing and gentle low-angle, low-energy ion milling while cooling the sample, the effects from specimen preparation are reduced resulting in higher quality of the TEM study. In the process of making face-to-face cross-section specimens by tripod polishing, it is crucial that the glue layer attaching the slabs of material is very thin (< 50 nm).