Light emitting diodes: the future lighting source with high efficiency

Recent developements for highly efficient ligth emitting diodes are introduced. Multi-quantumwell structure to improve the internal quantum efficiency, chip fabrication techniques to increase the extraction efficiency, and packaging techniques with phosphor distribution optimization are combined to obtain the efficient LEDs. Comparison between the several leading products in the market has been performed to reveal the current LED techniques. The internal quantum efficiency is found to be related to not only the dislocation density, but also the defect size and type. Some key factors are reviewed on the reliability of LEDs which recently has been improved a lot. For general lighting application, LM-80 test becomes the industry standard and will be introduced briefly.