Details of the Initiative

Green devices are a generic term for devices and technologies that help preserve the environment, including “energy creation,” “energy conservation,” and “energy storage.” The term “green” refers to “color and freshness” as well as the concept of “preserving (protecting) the environment.” In order to cope with resource depletion and environmental pollution, our laboratory of the Department of Electronics and Bioinformatics is developing materials, processes, and device technologies for green devices using “eco-friendly semiconductors,” which are composed of elements that are abundant on earth and have minimal toxicity to living organisms and the environment. Currently, rare metals and materials containing toxins are used for widely used visible light-emitting devices. Si-based semiconductor materials, such as Si and SiC, are abundant in resources and non-toxic, so they are used in many optoelectronic devices. However, their low luminous efficiency is a problem. Nanoparticulate Si-based quantum dots display strong visible light emission and can be used as light-emitting devices. Application to quantum computers and biomarkers is also under consideration. “Green devices” is a field where we can take advantage of the strengths of Japan’s semiconductor technology, which has been actively adding environmentally friendly functions to electric products, and is an industrial field that is expected to lead the global economy in the future.

The elemental composition (mass%) of the earth’s crust. Our laboratory is conducting research on environmental semiconductors, such as Si, SiC, AlN, ZnO, Mg2Si, and β-FeSi2, which are composed of elements that are abundant on the earth and have minimal toxicity to living organisms and the environment.

We have been creating an environment in which we can repeat the process of the design of the element structure using first-principles calculations and TCAD device simulations, trial manufacture, and evaluation of devices.

Physical properties of 4H (hexagonal)-SiC crystal (bulk) and SiC quantum dots are compared. Compared to 4H-SiC crystal, SiC quantum dots displayed a light emission shifting from green to light blue with a shorter wavelength and emission intensity increased in double digits. The physical model is verified from the results of first-principles calculations.

Two student presentations at the TACT 2023 conference in Taiwan received the Poster Award of Excellence Research results on “energy-saving” device structures and “energy-storing” device materials using Mg2Si and ZnO.