RESEARCH
Development of dielectric film technology for ultra-low-loss wide-gap semiconductor power devices
The energy problem is the greatest challenge of this century, and its solution requires an improvement in the performance of the power devices that control the transport and conversion of electrical energy. Widegap semiconductors such as silicon carbide (SiC), gallium nitride (GaN) and gallium oxide (Ga2O3) are emerging as new materials that can break through the theoretical limits of today's dominant silicon power devices. The promise of these wide-gap semiconductors is miniaturization of power devices and energy savings. We are particularly involved in the research and development of metal-oxide-semiconductor (MOS) power devices, which are the mainstay of switching devices. Specifically, we are exploring ideal dielectric film formation process through atomic-scale control of surface-interface reactions, with the aim of realizing high-performance and high-reliability MOS devices.
Quantum technology utilizing single photon source and spin defect in semiconductors
Quantum communication with complete confidentiality and quantum computing that realizes ultra-fast computation are expected to be key technologies that will shape the future society. The key to these technologies is a single photon source and spin defects. They are derived from defects in widegap semiconductors. A typical example is the nitrogen-vacancy center (NV center) in diamond, which is attracting a lot of attention as a system that can maintain its quantum state even at room temperature. With a view to future implementation and integration of quantum devices, we are working on the development of promising defects in SiC, for which crystal growth, processing and device technologies have been established. Specifically, our challenge is to build unconventional devices based on the fundamental principles of quantum mechanics by establishing a method to form defects and to realize flexible control of their luminescence and spin properties.
Low-power optoelectronic fusion devices using group IV mixed semiconductors
Existing information and communication systems are reaching their limits in terms of transmission and processing capacity as the digitalization and IOT of society accelerate. The fusion of electronics and photonics is expected to be a technological innovation that overcomes this limitation. By integrating optical devices with electronic devices, it is possible to increase the speed of information communication and achieve ultra-low power consumption. In addition, applications in quantum information technology, bio-sensing, and ultra-high-speed image sensors are expected. We are conducting research and development of optoelectronic fusion devices using germanium (Ge) and germanium tin (GeSn), which are group IV materials such as silicon, with the goal of achieving a true fusion of electronics and photonics.
Elucidation of spin and optical properties of semiconductor defects using supercomputers
Defects in semiconductor materials, such as substitutional atoms and vacancies, act as dopants, carrier traps, and recombination centers, and determine the performance of electronic and optical devices. Defects also act as single-photon and spin-quantum light sources. They are of interest for applications such as quantum computing. The flexible formation, control, and manipulation of defects requires a detailed understanding of their microscopic structures, spin, and optical properties. We are working to elucidate the physical properties of defects through the treatment of the interaction between nuclei and electrons in materials by means of ab-initio calculations on supercomputers. We seek to gain knowledge directly relevant to materials and device design by working on the theoretical elucidation of defects in wide-gap semiconductors and at the insulator/semiconductor interface.