Scientists have developed and tested a new imaging technique that reveals the atomic structure of thin films with unprecedented resolution. For the first time, the technique has shown very precisely how the atoms of the first layers of a film rearrange under the action of the substrate on which the film is grown. The results of the study are reported as the cover story of the October issue of Nature Materials.
Above: Electron density map of one of the layers of the gadolinium oxide film close to the gallium arsenide substrate (top) and a layer in the substrate (bottom), by using the COBRA imaging technique. A comparison of both maps shows that the gadolinium atoms (around the yellow-red peaks) rearrange so that the maps mimic each other
“This technique directly provides a very precise image of atomic positions within a film and at the interface between a film and a substrate,” says Ron Pindak, a physicist at the National Synchrotron Light Source (NSLS) at the U.S. Department of Energy’s Brookhaven National Laboratory and one of the authors of the study. “With the current growing interest in the study of nanomaterials, which are the size of a few atoms, this technique will probably be key in devising such materials and understanding their properties.”
Thin films are currently used in many technologies, including electronic chips, coatings, and magnetic recording heads. To improve the properties of these materials and create even thinner structures – such as smaller electronic chips – scientists are now trying to understand how the films interact with the substrate on which they are grown.
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