KENBIKYO Vol.52▶No.1 2017
■Feature Articles: Current Status of Electron Phase Imaging

In situ Electron Holography Observation of Electric-Potential Changes Inside a Solid-State Electrolyte

Tsukasa Hirayama, Yuka Aizawa, Takeshi Sato, Craig. A. J. Fisher, Ryuji Yoshida, Kazuo Yamamoto and Hidekazu Murata

Abstract: A thin specimen of an amorphous lithium phosphorus oxynitride (LiPON) solid-state electrolyte sandwiched between two copper (Cu) plates was prepared using focused ion beam milling and narrow Ar-ion beam milling. In situ electron holography was used to observe changes of phase distributions in the LiPON film when different voltages were applied. Several models of electric potential distribution inside the specimen were tested and the resulting phase distributions simulated by integrating the 3D potential distribution along the electron trajectory through the thin Cu/LiPON/Cu region and external electric fields leaking from the specimen. The electric potential model that provided the best match to the experimental phase measurements was taken to represent the correct potential change within the specimen. Based on the precise potential changes, lithium-ion and lithium-vacancy distributions inside the LiPON layer were inferred.

Key words: electron holography, electric-field leakage effects, 3D-boundary-charge method, solid electrolyte, electric-potential distribution changes