GaN-Free LEDs Offer UV Emission

Researchers at NTT Basic Research Laboratories and NEL TechnoSupport, both in Atsugi, Japan, have obtained 350-nm emission from a GaN-free, AlGaN single-quantum-well LED. They presented their work in the Jan. 6 issue of Applied Physics Letters.

To improve the extraction efficiency and the external quantum efficiency of the UV LEDs, they replaced the GaN in the structure with AlGaN buffer and contact layers. They fabricated the devices on a sapphire substrate using low-pressure metallorganic vapor phase epitaxy. The final devices displayed an external quantum efficiency of approximately 1.4 percent, with room-temperature CW output of 1 mW at an injection current of 20 mA and a maximum output of 7 mW at 220 mA.