RIKEN and Saitama big developed 227.5nm wavelength ultraviolet LED light intensity is about 50 times the original

[BP] the agency reports of physical and Chemical Research Institute and Saitama University jointly developed a light emitting wavelength of 227.5nm UV LED, the output power is 0.15mW. Prior to this, other research groups have released a luminous wavelength of 210nm UV LED, but the output power is only 0.02 W. In addition to the products, physical and Chemical Research Institute and the Saitama University has successfully developed the luminescence wavelength is 253nm, the output power is 1mW, emission wavelength is 261nm and power is 1.65mW, emission wavelength is 273nm and power for three kinds of UV LED 3.3mW. The output power of these UV LED, and the use of blue, red, white LED on the same, reaching the level can be used directly as a bactericidal lamp. The development of UV LED, the future will be intended for sterilization, water purification, medical fields, as well as hazardous substances in the field of high-speed decomposition, etc., so will further improve efficiency and power.

Trial of UV LED using AlGaN semiconductor. Firstly, the AlN layer is generated on the sapphire substrate, and then the N layer, the AlGaN light emitting layer (3 quantum well structure) and the P type AlGaN layer are formed on the top layer by layer. In order to improve the output power, the crystallization method of the AlN layer on the sapphire substrate is also improved. The AlN layer formed by the continuous supply of Al material at the same time and the continuous supply of the Al layer and the AlN layer generated by the ammonia gas are staggered to obtain a plurality of AlN layers. The crystal growth method is named as "the intermittent growth of ammonia by multi layer growth".

By intermittent supply ammonia multilayer growth method, (1) AlN crystals through dislocation density can be reduced; (2) flat crystal layer can be improved; (3) the deformation in the crystal resulting in crack to reduce. Because of the improvement of the quality and flatness of the AlN layer, the quality and flatness of the layers produced on the AlN layer have been improved, and the luminous intensity of the AlGaN layer is increased. Compared with the AlN layer generated by the original method, the luminous intensity is increased to about 50 times.

The UV LED is RIKEN RIKEN new research field of terahertz optical system of terahertz quantum unit project research group leader Hirayama Hideki and Professor Kamada Norihiko of Saitama University science and engineering research development achievement.