Abstract
For young people at HKUST, it is worth explaining how GaN and related materials have affected our lives. The most important application of GaN and related nitride materials has been the development of blue LEDs. Portable game machines, cellular phones and smart phones are very common items, especially among young people. The world’s first portable game machine was released in 1979 and cellular phones first became commercially available in 1984. However, until the end of the 1990s, all the displays of portable game machines and cellular phones were monochrome. Thus, it should be emphasized that the younger generation can now enjoy full-color portable games and cellular/smart phones because of the development of blue LEDs. Today, the applications of blue LEDs are not limited to displays. In combination with yellow phosphors, blue LEDs can act as a white light source and are used in general lighting. By 2020, about three-quarters of the incandescent and fluorescent lamps in Japan will have been replaced with LED lighting systems, resulting in a reduction of electricity consumption by 7% in principle. Therefore, the speaker would like to recommend that people in Hong-Kong to use LED lighting systems.
The applications of GaN and related materials are not limited to blue LEDs. They can be used for deep-UV (DUV) LEDs by utilizing Al-containing AlGaN. According to a UNICEF report, 663 million people still cannot drink safe water, and 2.4 billion people do not use safe sanitation facilities. In addition, global warming is causing an increase in the number of bacteria in drinking water even in developed countries. AlGaN-based DUV LEDs are effective for the low-cost and simple sterilization of water. Recently, DUV LEDs with an output power of over 50 mW/chip have been realized, which can now be installed in compact water purification systems.
Another application of these materials is laser diodes (LDs). Nitride-based violet LDs are the light source of the large-capacity optical storage systems called Blu-ray discs. Today, nitride-based LDs combined with phosphors can be used for the long-distance beam headlamps of vehicles. This material system is also useful for electron devices. In mobile or smart phone base stations, high-frequency RF amplifiers employing GaAs-based heterojunction field-effect transistors (HFETs) are being replaced with those employing GaN-based HFETs because of their capability of higher-power operation. By replacing Si-based insulated gate bipolar transistors and super-junction MOSFET power devices with GaN-based power devices in inverter and converter circuits, we can expect a 9.8% reduction in electricity consumption in Japan.
In this presentation, the speaker would like to explain the future prospects for new applications of group III nitride semiconductors and their contribution to establishing a sustainable society.
About the speaker
Prof Hiroshi Amano received D.Eng from Nagoya University in 1989. Currently he is a Director, Center for Integrated Research of Future Electronics, and a Professor, Institute of Materials and Systems for Sustainability, Nagoya University. In 1985, he developed low-temperature deposited buffer layers which provided the technology vendors to the development of high-quality group III semiconductor based LEDs and LDs. In 1989, he succeeded in growing p-type GaN and fabricating p-n junction LEDs for the first time in the world. He has published more than 529 technical papers and contributed to 27 books. Awards received include: 1994 Optoelectronics Conference Special Award, 1996 IEEE/LEOS Engineering Achievement Award, 1998 Japan Society for Applied Physics C Award, 1998 Rank Award, 2001 Marubun Academic Award, 2002 Takeda Award, 2003 SSDM paper award, 2009 Fellow, Japan Society of Applied Physics, 2011 IOP Fellow, 2014 Nobel Prize in Physics, Order of Culture, Japan, and 2015 NAE Foreign Membership.
|
