Zinc-based semiconductors point to new lasers and LEDs

Undertaken at North Carolina State University with input from the US Army Aviation & Missile Research, Development & Engineering Center, the research could lead to efficient ultraviolet (UV) lasers and LED devices for use in sensors and drinking water treatment, plus new ferromagnetic devices.

‘The challenge of using ZnO to make these devices has stumped researchers for a long time, and we’ve developed a solution that uses some very common elements: nitrogen, hydrogen and oxygen,’ said Dr Lew Reynolds, co-author of a paper describing the research and a teaching associate professor of materials science and engineering at NC State.

‘We’ve shown that it can be done, and how it can be done – and that opens the door to a suite of new UV laser and LED technologies,’ said Dr Judith Reynolds, a research scientist at NC State and lead author of the paper.

‘N-type’ materials and ‘p-type’ materials are required to make laser and LED technologies. N-type materials contain free electrons whilst P-type materials have ‘holes’ that attract those free electrons. But the holes in the p-type materials have a lower energy state, which means that electrons release their excess energy in the form of light as they travel from the n-type material to the p-type material. The shedding of excess energy at the so-called ‘p-n junction’ is what produces light in lasers and LED devices.