New processing technique for brighter, resilient LED

By coating polar gallium nitride with phosphonic groups, the researchers increased luminescence without increasing energy input.

NORTH CAROLINA, US: Research team at North Carolina State University have developed a new processing technique that makes light emitting diodes (LEDs) brighter and more resilient 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. The phosphonic groups also improve stability, making the GaN less likely to degrade in solution. Making the GaN more stable is important because that makes it more viable for use in biomedical applications, such as implantable sensors,” said Stewart Wilkins, PhD student, North Carolina State University.

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.

© North Carolina State University News