Potential and Latest Development of Nitride Semiconductors(<Special Issue> Where are the Materials for Ultraviolet Devices and Where are These Going ?)

Abstract

Physical properties of nitride semiconductors are compared with other typical semiconductors. Developments of blue-green LEDs and blue-violet LDS are reviewed. Latest efforts to develop shorter wavelength LEDs and LDS with both shorter and longer wavelength are introduced. Low temperature growth and electrical and optical characterization of high quality InN films on sapphire by RF-MBE aredemonstrated. Using this high quality InN films, it is found by photoluminescence and optical absorption measurements that band-gap of InN is around 0.8 eV, which is much narrower than the reported value of 1.9 eV. Latest developments of high power and high frequency AIGaN/ GaN HFETs are also reported in this paper, which confirms high potential of nitride semiconductors in the application to high power and high frequency electronics fields. Finally, it is emphasized that studies on crystal growth technology and characterization are very important in developing wide variety of new generation electronic and optoelectronic devices using nitride semiconductors.