Our target is to develop new electronic materials which can open up novel device applications. The materials of our current interest are nitride semiconductors, InGaAlN mixed crystal system, which is well known as materials for blue lightemitting- diodes (LEDs). Taking advantages of our epitaxial growth reactors developed by ourselves and a series of device fabrication equipment, we are going toward the further contribution to the global societies in terms of the energy saving, by developing high-power electronic devices and high-efficiency light-emitting devices.
Since our first proposal of InGaAlN system for wide-spectral-range light-emitting devices in 1987, we have continued the research on the epitaxial growth of this system, estimation of its miscibility gap, proposal of novel substrates for the epitaxial growth and utilization of various crystallographic orientations to control its growth behaviors and properties. Also we found the true band-gap of InN of 0.7 eV which was much lower than the previously reported value. We are now concentrating on the development of high-performance laser diodes for optical communications systems by the pressurized-reactor metalorganic vapor phase epitaxial growth of InN, and the improvement of the efficiencies of optoelectronic devices by the nitrogen-polar epitaxial orientation of InGaAlN as well as new substrates with exotic materials such as ZnO and ScAlMgO4.