Mistakes can be beautiful in the HelsinkiALD group—a lab focused on atomic layer deposition at the University of Helsinki. Doctoral researcher Alexander Weiß made this multicolor film by accident after depositing thin layers of hafnium oxide. The goal was to make a totally smooth film of atoms, but the range of colors on the substrate reveals that the film has a slightly varied thickness across its surface, each level of thickness amplifying a different wavelength of the ambient white light. (The same thing makes the rainbow patterns on soap bubbles.) “So on a nanometer scale this would compare to a mountain-valley landscape, which makes the film look nice but otherwise useless.” Weiß says. As an example of what a thin film ideally looks like, you can see one of his smoother, single-color films made of aluminum oxide below.
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This story was updated on June 24, 2022, to correct Alexander Weiß's position. He is a doctoral researcher, not a postdoc.