News Article
Brightening and strengthening GaN LEDs
Scientists have reported that adding phosphonic groups increases luminescence and enhances the stability of the gallium nitride based devices
Researchers from North Carolina State University have developed a new processing technique that makes LEDs brighter and more resilient by coating 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,” 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."
“Making the GaN more stable is important,” Wilkins adds, “because that makes it more viable for use in biomedical applications, such as implantable sensors.”
By coating polar GaN with phosphonic groups, the researchers increased luminescence without increasing energy input. (Image: Stewart Wilkins)
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 work has been described in the paper, “In Situ Chemical Functionalization of Gallium Nitride with Phosphonic Acid Derivatives during Etching,” by Stewart J. Wilkins et al in Langmuir, 2014, 30 (8), pp 2038–2046. DOI: 10.1021/la404511b
The research was supported in part by the National Science Foundation under grant EEC 1156762.
“By coating polar GaN with a self-assembling layer of phosphonic groups, we were able to increase 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."
“Making the GaN more stable is important,” Wilkins adds, “because that makes it more viable for use in biomedical applications, such as implantable sensors.”
By coating polar GaN with phosphonic groups, the researchers increased luminescence without increasing energy input. (Image: Stewart Wilkins)
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 work has been described in the paper, “In Situ Chemical Functionalization of Gallium Nitride with Phosphonic Acid Derivatives during Etching,” by Stewart J. Wilkins et al in Langmuir, 2014, 30 (8), pp 2038–2046. DOI: 10.1021/la404511b
The research was supported in part by the National Science Foundation under grant EEC 1156762.
