Published on March 24th, 2014 | by James Ayre3
Brighter, More Resilient LEDs Via New Processing Technique
March 24th, 2014 by James Ayre
The improvements are achieved by coating the semiconductor material gallium nitride (GaN) with a layer of phosphorus-derived acid.
“By coating polar GaN with a self-assembling layer of phosphonic groups, we were able to increase luminescence without increasing energy input,” states Stewart Wilkins, a PhD student at NC State and lead author of a paper detailing the new work. “The phosphonic groups also improve stability, making the GaN less likely to degrade in solution.
“Making the GaN more stable is important,” Wilkins continues, “because that makes it more viable for use in biomedical applications, such as implantable sensors.”
The press release from North Carolina State University provides the details:
The researchers started with polar GaN, composed of alternating layers of gallium and nitrogen. To increase luminescence, they etched the surface of the material with phosphoric acid. At the same time, they added phosphonic groups — organic molecules containing phosphorus — that self-assembled into a monolayer on the surface of the material. This layer further increased luminescence and improved the stability of the GaN by making it less likely to react chemically with its environment.
The new research paper describing the work — In Situ Chemical Functionalization of Gallium Nitride with Phosphonic Acid Derivatives during Etching — was published online in the journal Langmuir.
The work was supported in part by a grant from the National Science Foundation.
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