Researchers’ Claim 50% Improvement in LED Efficiency

July 31, 2017
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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 has 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. They can also help reflect light out of the device, preventing it from being trapped inside and wasted.
The main growth chamber of the molecular epitaxy beam apparatus used to make the nanoparticle-infused gallium nitride semiconductors. The semiconductors could boost LED efficiency by up to 50 percent, and even lead to invisibility cloaking devices. Image credit: Joseph Xu, Michigan Engineering The main growth chamber of the molecular epitaxy beam apparatus used to make the nanoparticle-infused gallium nitride semiconductors. The semiconductors could boost LED efficiency by up to 50 percent, and even lead to invisibility cloaking devices. Image credit: Joseph Xu, Michigan Engineering. 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 Rachel Goldman, U-M professor of materials science and engineering, and physics. “The ability to make 3-D structures with these nanoparticles throughout is going to open a lot of possibilities.” The idea of adding nanoparticles to increase LED efficiency is not new. But previous efforts to incorporate them have been impractical for large-scale manufacturing. They focused on pricey metals like silver, gold and platinum. In addition, the size and spacing of the particles must be very precise; this required additional and expensive manufacturing steps. Furthermore, there was no cost-effective way to incorporate particles below the surface. Former materials science PhD student Sunyeol Jun prepares the molecular beam epitaxy apparatus that’s used to make the nanoparticle-infused gallium nitride semiconductors. The semiconductors could boost LED efficiency by up to 50 percent, and even lead to invisibility cloaking devices.

Former materials science PhD student Sunyeol Jun prepares the molecular beam epitaxy apparatus that’s used to make the nanoparticle-infused gallium nitride semiconductors. The semiconductors could boost LED efficiency by up to 50 percent, and even lead to invisibility cloaking devices. Goldman’s team discovered a simpler way that integrates easily with the molecular beam epitaxy process used to make semiconductors. Molecular beam epitaxy sprays multiple layers of metallic elements onto a wafer. This creates exactly the right conductive properties for a given purpose. 

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