Yasuhiro Kimura

Title : Atomic migration-driven metal nanowire growth

Abstract:

Metallic nanowires, also called whiskers, are next-generation materials that are expected to revolutionize the functionality of materials by improving the performance of existing devices due to their unique physical properties at their own microscopic scale. The application of metallic nanowires is expected to include the development of high-strength structural materials that take advantage of the small number of crystal defects that reduce strength due to their extremely small size, their use as optical waveguides for optoelectronics that utilize surface plasmon propagation, and their application as metamaterials for realizing negative refractive indices. etc. are expected to be developed. Nevertheless, the application of metallic nanowires remains at the laboratory level. The essential technological issue that is slowing down industrial applications is the fact that the principle of creating pure metal nanowires has not yet been established. Noted that, for nanowire growth, the "growth driving force" of how to supply atoms and the formation of a "growth nucleus" as a singularity of how to eject atoms in only one dimension are important, but this is unclear for pure metals. The nanowires reported so far are semiconductors such as Si or metal oxides such as Fe2O3, and the principle of crystal growth by chemical vapor deposition (CVD) is widely used. In this CVD approach, the growth driving force is given in the gas phase and controlled as partial pressure, and the growth nuclei are created by using metal catalysts. On the other hand, for pure metals with low vapor pressure, the CVD-based nanowire creation method used for semiconductors and metal oxides is not applicable, and the establishment of a novel growth technique has been required. This study introduces a knowledge for metal nanowire growth technique based on the atomic diffusion which is an atomic transportation phenomena due to the chemical potential gradient induced by electric, thermal, and stress field.

Audience take Away:

•  Learn where we stand in metallic nanomaterials research
•  Learn the difference from general semiconductor nanowire growth methods
•  Learn about the phenomenon of atomic diffusion as a new knowledge for nanowire growth

Biography:

Dr. Kimura studied Mechanical Engineering at Tohoku University, Japan and graduated as MS in 2014. He joined the research group of Prof. Saka at the Tohoku University, Japan, and took part in the group of Prof. Cola at the Georgia Institute of Technology, US to learn the nanomaterial synthesis and device application as a visitor researcher for short term. From 2015-2017, he received the JSPS Research Fellowship for Young Scientists DC2. He received his PhD degree in 2017 at the Tohoku University. He obtained the position of an Assistant Professor at the same institution in 2017-2019, and at the Nagoya University in 2019-present. He has published more than 45 research articles.