Reseach

Various crystal defects exist in wide bandgap semiconductor materials such as diamond and silicon carbide (SiC). By controlling the spin and light emission of crystal defects, quantum computers that far exceed conventional computing power, high-brightness optical devices whose size is controlled at the nano-level, and ultra-sensitive quantum sensors (magnetic field, temperature, etc.) are expected to be realized.

In this research project, we will develop a technology to efficiently and precisely form nitrogen-vacancy (NV) centers in diamond and silicon vacancies (V_Si) in SiC by using electron and ion beams. We are conducting research on applying the formed NV and V_Si as quantum sensors. We participate in the flagship project (technical area: quantum measurement/sensing) of the ``Optical and Quantum Leap Flagship Program (Q-LEAP)'' as research to apply it as a quantum sensor.

• NV centers in diamond, known as quantum sensors, can be used for ultra-sensitive magnetic sensors. In this research project, we succeeded in forming the world's highest concentration of NV centers by irradiating them with an electron beam. We are currently developing NV center formation technology suitable for the development of magnetoencephalography and magnetocardial measurements using the NV center.
• V_Si in silicon carbide can also be used as a quantum sensor. In this research project, we can irradiate SiC with a focused proton beam and form VSi at any location within a power device. We are developing a system that monitors the current and temperature of power devices by using the V_Si as a quantum sensor.

Nitrogen-vacancy (NV) centers in diamond can be used as qubits that operate at room temperature. In 2005, it has been reported that NV centers are formed using ion implantation. In 2009, we began developing a technology for forming NV centers using ion implantation, with the aim of realizing a quantum resistor that operates at room temperature. In 2013, it became possible to form a single NV center by nitrogen ion implantation, which has the longest coherence time (2 ms) of any NV center formed by ion implantation. In 2013, we succeeded in forming two qubits of NV-NV using nitrogen molecule ion implantation. 

In 2019, we developed an organic ion implantation technology using adenine (C₅N₅H₅) molecules as the raw material (patent application filed in 2018, patented in 2023), and succeeded in converting NV-NV-NV into three qubits for the first time in the world. In May 2022, we developed a phthalocyanine (C₃₂N₈H₁₈) ion beam and are working to further increase the number of qubits. In 2023, we will develop an organic ion beam using L-arginine hydrochloride (C₆H₁₄N₄O₂・HCl) .

SiC is expected to be applied to devices with higher efficiency and lower loss than conventional silicon (Si) semiconductors. At the same time, it is attracting attention as an extreme environment semiconductor that can operate stably even in harsh environments that exceed the limits of Si. This research project is conducting research on the development of radiation-resistant SiC devices with the aim of applying SiC, which has excellent characteristics, to semiconductor devices that operate stably and with high reliability even in space and nuclear facilities. Masu. In addition, semiconductor devices such as integrated circuits (LSI) and solar cells used in artificial satellites and space stations are subject to property deterioration, malfunction, and destruction due to the large amounts of radiation (heavy ions, proton beams, electron beams, etc.) present in space. occurs. This research project is developing diagnostic technology to accurately evaluate the radiation resistance of semiconductor devices, and using the developed technology to elucidate the mechanisms of radiation deterioration, malfunction, and destruction of semiconductor devices for space use, and to further improve radiation resistance. We are conducting research on strengthening technology.