Prof. New Industry Creation Hatchery Center (NICHe), Tohoku University
Today's advanced information society is supported by the electronics technology.In particular, the optical fiber communication system is most important.The present high-bit-rate and long-haul optical communication system has been achieved with the distributed feedback (DFB) laser which shows the single-longitudinal mode oscillation very different from the previous Fabry-Perot laser. Matsuoka succeeded in the first CW operation of this DFB laser with the wavelength of 1.55µm in 1981.He transferred the fabrication technique to device fabrication companies.He also pushed the system experiments by fabricating hundreds of DFB lasers suitable for the transmission. Finally, the bit-rate and the connection interval have increased to 25,000 times and one order magnitude longer, respectively.
The electronics technology is supported by the development of electronic materials.The advent of new electronic materials will revolutionize electronics. Our laboratory is engaged in research and development of new electronic materials with the aim of contributing to the development of devices with new functions. The research target is a “Nitride Semiconductor.” This material is famous for its application to blue light-emitting-diodes (LEDs), in addition, it can be expected to have a wide range of other applications.
Matsuoka proposed using InGaAlN as a materials enabling the fabrication of the brilliant LEDs in 1987. He also succeeded in growing the first single crystal of InGaN which emitted blue light. In this growth, he developed the growth conditions for the growth of InGaN with metalorganic vapor phase epitaxy (MOVPE). His proposal and growth technique made a great contribution to fabricating blue light-emitting-devices. Matsuoka has also promoted to study the epitaxial growth of InGaAlN by MOVPE. As a result, the following achievements were obtained.
- Prediction of miscible regions in InGaAlN from a crystallographic point of view
- Proposals for various epitaxial growth substrates
- Understanding the effect of crystal polarity on crystal growth and epitaxial layers
In addition, Matsuoka found that the InN band-gap is in the infrared region rather than the visible region experimentally shown previously.Currently, he are proceeding the pressurized epitaxial growth of InN and its application of optical devices. We are exploring the possibility of application to laser light sources for communication.Our efforts can be classified into the following three themes.
- High quality optical and electronic devices using N-polar InGaAlN
- Higher performance of nitride devices by using exotic substrates and processes