March 25, 2014...North Carolina State University Researchers found that coating gallium nitride (GaN) with a layer of phosphorous-derived acid can make LEDs that are both brighter and more resilient than traditional white LEDs.“By coating polar GaN with a self-assembling layer of phosphonic groups, we were able to increase the luminescence without increasing energy input, ” says Stewart Wilkins, a Ph.D. student at NC State and lead author of a paper describing the work. “The phosphonic groups also improve stability, making the GaN less likely to degrade in solution."
The researchers began the process with polar GaN made up of alternating layers of gallium and nitrogen. They utilized phosphoric acid to etch the material's surface for increased luminescence, and they also added organic molecules containing phosphorous (phosphoric groups) that self-assembled into a monolayer on material's surface. This layer further increased luminescence and made it less likely to chemically react with its environment.
“Making the GaN more stable is important, ” Wilkins added, “because that makes it more viable for use in biomedical applications, such as implantable sensors.”
The details of the development were published online in the journal Langmuir. The research was partially funded by the National Science Foundation under grant EEC 1156762.