• 1. Development of Distributed Feedback (DFB) Laser Diodes (LD) widely used in optical communications systems realizing a highly information-based society. This LD increases the transmission capacity by 25,000 times per fiber which means the bit rate of 10Tb/s.
• 2. Nitride semiconductors famous for blue light emitting diodes.
• (a) Proposal of InGaAlN system considering device applications in 1989
• (b) Success in growth of single crystalline InGaN by metalorganic vapor phase epitaxy (MOVPE) in 1989
• (c) Prediction of band-gap energy (Eg) of InN much smaller than the values reported in 1980s and its 　 experimental confirmation in 2002
• (d) Observation of photoluminescence from InGaN in 1991
• (e) Prediction of phase separation in InGaAlN in 1997

DFB-LD: Fabrication of periodic structure with submicron scale, Epitaxial growth of semiconductor films on the substrate with fine structures, LD fabrication process, device evaluation, and device simulation

Nitride Semiconductors: MOVPE growth, N-polar growth, Evaluation of semiconductor materials, Fabrication of light-emitting devices, solar cells, and high-power transistors

• Atomic diffusion bonding of two flat wafers with thin metal films is a promising process to achieve wafer bonding at room temperature. High surface energies of metal films and a large atomic diffusion coefficient at the grain boundaries and film surfaces enable bonding at room temperature without unusually high loading pressure. This technique, which enables bonding of any mirror-polished wafer, is gaining wider use for fabricating optical and electrical devices. Moreover, bonding of mirror polished metals and polymer sheets can be achieved, which further extends the application of this bonding technique.

Optical, power and electrical devices, MEMS, bonding of polymer sheets, metals, and ceramics for precision mechanical equipments.

• Phase change random access memory (PCRAM) has attracted attention as next-generation non-volatile memories. A conventional PCM is Ge-Sb-Te which shows a fast crystallization speed and an excellent reversibility of phase transition. However, Ge-Sb-Te has a low crystallization temperature of about 150 ºC and a high melting temperature of over 600 ºC , which limits data retention and causes high power consumption, respectively.
• We have developed a new phase change materials with high crystallization temperature and low melting point such as Ge-Cu-Te etc, which have high potential as PCRAM materials with high thermal stability and low power consumption (Fig.1,2).

Our materials are developed for PCRAM, DVD recording materials etc. We hope the collaboration research with companies which are interested in our developed phase change materials.

• Tactile sense and the sense of touch are multiple combinations of fundamental sensations, such as smooth and rough, soft and hard, dry and wet, and hot and cold sensations. These sensations are described with the information on force, distortion, temperature, stickiness and oscillation.
• A tactile sensor corresponding to several types of human skin sensory receptors and an active tactile sensor system that is an integrated sensor structure imitating human haptic motions have been developed. These sensor systems allowed measurement of "Kansei" words that are extremely vague tactile feelings, and roughness, softness and temperature sensations. However, tactile sense or the sense of touch also includes other sensations and combinations of them. Therefore, to develop a sensor, it is important to define how the sensations and physical information relating to the sensations are obtained and what relationships exist between them.
• In this research, the relationships between sensations, including fundamental sensations that have already been obtained and other sensations, and the relevant physical information are being investigated. Additionally, on the basis of the knowledge through the investigation, an advanced sensor system that allows obtaining haptic information is being developed.

The research is beneficial not only to life science but also to manufacturing fields.