Preparation of plan-view Co-doped FeSi thin film TEM specimens using FIB

When examining thin films using transmission electron microscopy (TEM), it is usually necessary to image a cross-section of the film (i.e. parallel to the film). However sometimes it is favourable to image thin films in plan-view (i.e. perpendicular to the film). This is the case for Co-doped FeSi thin films, which possess chiral symmetry along certain zone axes. In order to view these zone axes it is necessary to prepare the films in plan-view. There exist various ways to produce plan-view TEM specimens of thin films, such as back etching, ion milling and mechanical polishing. Here, a method using focused ion beam (FIB) is described in detail. Benefits of using FIB are that it is a quick process, there are no limitations in terms of substrate material, and samples can be produced from sections of substrate/film that may be too small to prepare any other way. The effectiveness of the preparation technique is also discussed here, with some preliminary energy dispersive X-ray