• The main research subject of our group is developing material purification methods, crystal growth methods and detector fabrication technologies for compound semiconductor radiation detectors. Our group intensely studies a compound semiconductor, thallium bromide (TlBr), for fabrication of gamma-ray detectors for the advanced radiation applications. The attractive physical properties of TlBr lie in its high atomic number (Tl: 81, Br: 35), high density (7.56 g/cm3) and wide bandgap (2.68 eV). Due to the high atomic number and high density, TlBr exhibits high photon stopping power. The wide bandgap of TlBr permits the device low-noise operation at and above room temperatures.

Our group focuses on development of compound semiconductor radiation detectors for advanced radiation applications including ultra-high resolution PET systems, ultra-high resolution SPECT systems, photon counting CT systems and Compton cameras. We hope to conduct collaborative research with a willing company for a practical application of this technology in industry.

• Our research target is mainly focused on the topic of development of novel scintillator crystals, piezoelectric crystals, growth technology, characterization and its device application.
• We design and synthesize new materials from a view point of Crystal Chemistry, and investigate their structure and physical properties. We also study on photo-detector, as suitable photo-detector fully contribute to get maximum signal from scintillator. This activity is very important to realize practical application of our developed materials. Recently, piezoelectric material and high melting temperature alloy project is also started.

For the purpose of "real" contribution to human culture, we are always carrying out our research activity considering the industrial application. This point is unique feature of our attitude toward science.

• 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.

• Recently, with a spread of high definition video streaming services and ubiquitous network, development of high-quality, ultra-realistic and low-power display systems has been demanded. We have been studying physical properties of liquid crystal materials, precise control technique of polarization, high performance liquid crystal display (LCD) devices and its application to the advanced display systems for the realization of new media such as electric paper display and digital signage display, and low-energy society. We established a polarization control technology which realizes a precise control of polarization with liquid crystal materials. By using this world-leading technology, we have been studying the control of the surface alignment of liquid crystal molecules and developed a wide-viewing angle and fast switching liquid crystal display, ultra-high definition field-sequential-color display (Fig. 1), ultra-low power reflective full-color display (Fig. 2) and large-size high-quality display system.
• We are also studying the ultra-realistic display systems such as a spatial 3D display and a multiple directional viewing display based on the precise light control technique as a next generation interactive communication technologies (Fig.3). We hope to conduct collaborative research with a willing company for a practical application of this technology in industry.

• The cold spray (CS) technique is known as a new technique not only for coating but also for thick depositions. It has many advantages, i.e. dense coating, high deposition rate, low oxidation, and no phase transformation. We have been carrying out establishment of innovative preparing and coating techniques using the CS, and maintenance of reliability and safety of the cold sprayed repairing parts and coatings. Moreover, in order to evaluate the compatibility between a substrate material and particles based on an adhesion mechanism and scientific basis, various adhesion conditions are examined a micro / nano-structure observation and a molecular simulation.

Our targets were mainly hot section parts of thermal power plants and reactor piping and tubes etc. Recently, it is possible to make a ceramic coating. Therefore, we accelerate the evolution of the other fields including the creation of the functionality materials in near future.