Invisibility cloaks may be on the way with the addition of metallic nanoparticles to semiconductors.
Researchers from the University of Michigan created a new technique that could improve the efficiency of LED lighting by 50 percent while adding no cost during manufacturing. In addition, the new technique could enable cloaks that render objects partially invisible by inducing a phenomenon called reverse refraction, where light waves bend backwards in a way that doesn’t occur in nature, potentially directing them around an object or away from the eye.
The research team integrated nanoparticles with the molecular beam epitaxy process used to make semiconductors by spraying multiple layers of metallic elements onto a wafer to create exactly the right conductive properties for a given purpose.
Next, the scientists applied an ion beam between the layers to push metal out of the semiconductor wafer and onto the surface.
Controlling the size and placement of the nanoparticles was done by varying the angle and intensity of the ion beam. Applying the ion beam over and over between each layer created a semiconductor with the nanoparticles interspersed throughout.
“If you carefully tailor the size and spacing of nanoparticles and how deeply they’re embedded, you can find a sweet spot that enhances light emissions,” Myungkoo Kang, a former graduate student in Goldman’s lab and first author on the study, said in a statement. “This process gives us a much simpler and less expensive way to do that.”
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