Development of white LED fabricated by RGB phosphor and near ultra-violet LED

摘要

White light-emitting diode (LED), which consists of an InGaN-based blue LED and yellow fluorescent phosphor is already in practical use. The white LED made by a new technology of combining the near ultra-violet (NUv)-LED and fluorescent phoshor of the three primary colors (red (R), green (G), blue (B)) is promising for use in lighting. The white LED emitting three primary colors can have the high general color-rendering index and have a variety of color temperature. MITSUBISHI CABLE INDUSTRIES, LTD. has developed the new growth technique called LEPS (Lateral Epitaxy on a Patterned Substrate with stripe grooves), and applied it to fabricate the NUV- LED. Furthermore, jointly with STANLEY ELECTRIC CO., LTD, MITSUBISHI CABLE INDUSTRIES has experimentally fabricated the white LED with RGB phosphor and the NUV-LED as an excitation light source. As a result, due to the LEPS method, the dislocation density of GaN layer has been reduced to approximately 1.5×10{sup}8 cm{sup}(-2), the output power of the NUV-LED was 15.6mW, and the external quantum efficiency was approximately 24% (emission peak wavelength: 382 nm; flip-chip mounted; at room temperature; forward current: 20 mA). The properties of the white LED using this NUV-LED were as follows: the luminous efficiency of 8.2 lm/W, general color-rendering index of Ra = 86～90, and color temperature of 6900～7600 K (at room temperature, forward current: 20 mA).