Abstract

Abstract: The function and role of electronics are to transform energy, for example, from photon, chemical, bio, heat, and vibration energy to electric energy and vice versa, and also from DC to AC, AC to DC, and DC to DC electric energy. Highly efficient energy transformation is one of the highest-priority issues for electronics. I believe that group III nitride semiconductors are among the most promising materials for this purpose and for realizing a sustainable smart society. Their most important application is blue LEDs. Portable games machines and cellular or smart phones are very familiar items. Until the end of the 1990’s, all the displays of portable games machines and cellular phones were monochrome. The younger generation can now enjoy full-color portable games because of the emergence of blue LEDs. Today, applications of blue LEDs are not limited to displays. In combination with phosphors, blue LEDs can act as a white light source and are also used in general lighting. In Japan, about three-quarters of general lighting systems composed of incandescent and fluorescent lamps will have been replaced with LED lamp systems by 2020, by which we can reduce total electricity consumption by 7%, corresponding to a saving of 1 trillion Japanese yen per year. To achieve the practical application of blue LEDs, there were several barriers to overcome. In this lecture, I would like to explain how blue LEDs were developed in spite of these barriers. I hope that this presentation will suggest some directions to young people with visions for the future and the desire to realize their dream.