Japanese semiconductor lighting project based on ultraviolet LED and phosphor system

The light for the 21st century Japanese national project, which is based on the high-efficient ultraviolet (UV) light-emitting diode (LED) and phosphor systems, has started from 1998 in Japan. The proposal of UV white LED system for general lighting applications has for the first time in the world been done at August 1997 before start up the project. The outline and purpose of this project are introduced. This is also the brief summary of this national project based on white LEDs lighting, which has been carried out by the cooperation between universities and companies in the fiscal year 2000. In particular, we have demonstrated high-power UV LED having an external quantum efficiency of 24 % at an emission wavelength of 382 nm. With increasing forward-bias current, the output power increased linearly and was estimated to be above 38 mW at 50 mA. Basic illumination properties of the lighting sources using phosphor-based UV white LEDs are described.