A sandblaster at the atomic level

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4 min read
fairly difficult
Modifying surfaces by shooting particles at them - this technique, called 'sputtering', is indispensable in surface science. However, if the surface is not perfectly smooth and regular, it is hard to predict the result of the sputtering process. Scientists have now managed to explain the effect of particles on rough surfaces during sputtering - with implications for fusion research and even astrophysics.
If you want to remove a layer of paint from a metal surface, you can use a sandblaster: Countless grains of sand are blasted onto the surface, and what emerges is clean metal. "Sputtering" can be imagined in a very similar way -- only much smaller, on an atomic scale. The surface is irradiated with ions, i.e. charged atoms, allowing microscopic impurities to be removed, for example.

If you are dealing with perfect surfaces where all the surface atoms are arranged exactly in a smooth plane, established theoretical models can predict the effects of ion bombardment quite easily. But in practice, this is very rarely the case. For complicated, rough surfaces, it is difficult to say how much material will be removed during sputtering. A computational model developed by researchers from TU Wien now makes it possible to characterize the surface roughness in a simple way and thus correctly describe the sputtering process even for more complicated samples.

Removing or depositing thin layers

"Sputtering of surfaces by ion bombardment is a very popular and versatile technique," says Prof. Friedrich Aumayr from the Institute of Applied Physics at TU Wien. "On the one hand, it can be used to remove material very precisely, for example in semiconductor technology, to create perfectly clean surfaces. On the other hand, however, it can also be used to selectively evaporate any material, which is then deposited on another surface, for example to produce super-reflective eyeglass lenses or hard…
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