Invisibility cloak to be a reality soon A new technique that peppers metallic nanoparticles into semiconductors may help achieve the feat
Until recently, invisibility cloaks and the like were firmly in the realms of science fiction, but now, you may soon be able to live out your wildest Harry Potter dreams.
In an advance that could boost the efficiency of LED lighting by 50 percent and even pave the way for invisibility cloaking devices, a team of University of Michigan researchers developed a new technique that peppers metallic nanoparticles into semiconductors.
It’s the first technique that can inexpensively grow metal nanoparticles both on and below the surface of semiconductors. The process adds virtually no cost during manufacturing and its improved efficiency could allow manufacturers to use fewer semiconductors in finished products, making them less expensive.
The metal nanoparticles can increase the efficiency of LEDs in several ways. They can act as tiny antennas that alter and redirect the electricity running through the semiconductor, turning more of it into light. The process can be used with the gallium nitride that’s used in LED lighting and can also boost efficiency in other semiconductor products, including solar cells. “This is a seamless addition to the manufacturing process, and that’s what makes it so exciting,” said researcher Rachel Goldman. The U-M researchers applied an ion beam between these layers - a step that pushes metal out of the semiconductor wafer and onto the surface. The metal forms nanoscale particles that serve the same purpose as the pricey gold and platinum flecks in earlier research. Their size and placement can be precisely controlled by varying the angle and intensity of the ion beam. And applying the ion beam over and over between each layer creates a semiconductor with the nanoparticles interspersed throughout.
Because the technique allows precise control over the nanoparticle distribution, the researchers say it may one day be useful for cloaks that render objects partially invisible by inducing a phenomenon known as “reverse refraction.”
“For invisibility cloaking, we need to both transmit and manipulate light in very precise ways, and that’s very difficult today,” Goldman said. The team is now working to adapt the ion beam process to the specific materials used in LEDs.