Hitachi Cable develops 55-lumen red LED chips
The Japan-based chip and epiwafer manufacturer has developed a fine-line electrode structure to improve light extraction.
To resolve these problems in developing a new LED chip, instead of using larger electrodes, Hitachi Cable has utilized two pad electrodes for receiving power, a backbone electrode connecting the two electrodes, and multiple fine line electrodes that extend from the backbone electrode on the upper chip layer (see Fig. 2: "Structure of new high-power red LED").
By employing fine line electrodes, Hitachi Cable has succeeded in achieving uniform dispersion of current across the entire chip surface without blocking light from the light emitting layer, thus attaining a maximum luminous flux of 55 lumens in a large LED chip measuring 1 mm by 1 mm.
Hitachi Cable expects the new LED chip to find applications in display applications, as well as devices such as projectors. The company says it will continue to pursue active development of higher-power LED chips while expanding its lineup of high-power LED chips, including yellow and infrared LED chips.
Hitachi Cable manufactures and supplies AlGaAs (aluminum gallium arsenide) and AlGaInP (aluminum gallium indium phosphide) epitaxial wafers, which can be used to manufacture red LED chips. The company has also developed high-brightness red LED chips that form a metal reflector (MR) under the light-emitting layer. This product is currently being supplied to LED package manufacturers and other customers.