Ar ion milling system for the selective preparation of TEM specimen

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At the Materials Science Center of Philipps-Universität Marburg a double-aberration corrected scanning transmission electron microscope is operated (amongst other microscopes) in the user facility for electron microscopy of the university. This microscope is used mainly for research in the areas of novel functional materials, like semiconductors, ion conductors, and oxides. In several coordinated as well as individual projects different electron microscopic techniques are used - on the one hand to develop the electron microscopic techniques further and on the other hand to establish a structure <=> property relationship for the functional materials investigated. High resolution transmission electron microscopy, high resolution scanning transmission electron microscopy, electron energy loss spectroscopy are used as well as four-dimensional scanning transmission electron microscopy to characterize the materials and their interfaces quantitatively. Electron transparent samples are currently prepared either by milling using a focused Gallium ion beam or by milling with a broad Argon ion beam. Severe damage of the specimen surfaces is a result of both preparation techniques. These damaged layers make quantitative evaluation of data impossible. The damaged and ion implanted layers can be intentionally removed with the proposed ion mill using a finely focused Argon ion beam. This results in specimens for electron microscopic investigations, which are free from damaged surface layers and which are homogeneously thin. This not only helps to improve the quality of microscopic investigations, but also makes quantitative studies on composition and on electric fields possible, also across interfaces.