(Invited) Approaches for Mechanistic Understanding of Electrodeposition Processes for Fabricating Micro/Nano Structures and Devices

Abstract

Electrochemical deposition processes have precise controllability, selectivity and uniformity, and have been widely applied for fabricating various functional micro/nano structures and devices. In order to achieve further higher controllability for developing reliable process for manufacturing, molecular-level understanding of the deposition processes is required. Furthermore, this can be be also utilized to understand various applications such as the electrode processes of secondary batteries using metal anodes and so on. For this, we have attempted to apply theoretical approaches such as density functional theory (DFT) and kinetic Monte Carlo (KMC) calculations[1.2], as well as experimental methods such as surface enhanced Raman microscopy equipped with plasmonic sensors[3-5]. In this paper, these approaches with some of the resent results will be described. The analysis using DFT calculations provided the molecular-level insights for the catalytic activity of the electroless deposition reaction process at the surface, with the effects of the additive species and solvation. Also, in combination with the KMC calculation, multi-scale simulation for the nucleation and growth process at the Zn anode surface for the secondary battery was attempted. While these approaches enable quantitative discussion for the mechanistic understanding of the processes, we also attempted to obtain "real" data from experimental approaches. For this, we applied surface enhanced Raman scattering (SERS) and developed "plasmonic sensors" with controlled nanostructures to obtain high signal enhancement at electrode-electrolyte interface. We have developed two types of the plasmonic sensors which could achieve extremely high sensitivity. Multi-confocal type SERS microscopy was also developed for mapping and imaging analyses of the electrode surface as well as local pH distributions. By using these techniques, various processes at the electrode surfaces and interfaces have been investigated and modelling of the processes has been carried out.This work was financially supported in part by “Development of Systems and Technology for Advanced Measurement and Analysis” program from Japan Science and Technology Agency, and Grant-in-Aid for Scientific Research, MEXT, Japan.[1] Y. Onabuta, M. Kunimoto, H. Nakai, T. Homma, Electrochim. Acta, 307, 536 (2019).[2] Y. Onabuta, M. Kunimoto, S. Wang, Y. Fukunaka, H. Nakai, T. Homma, J. Electrochem. Soc., 169, 092504 (2022).[3] M. Yanagisawa, M. Saito, M. Kunimoto, T. Homma, Appl. Phys. Express, 9 , 122002 (2016).[4] M. Kunimoto, F. Yamaguchi, M. Yanagisawa, T. Homma, J. Electrochem. Soc., 166, D212 (2019).[5] T. Wang, M. Kunimoto, M. Yanagisawa, M. Morita, T. Abe, T. Homma, Energy Env. Mat., in press (2022).