Current Progress of Solid State Ionics on Information and Communication Device Technology Kazuya Terabe, Takashi Tsuchiya, Tohru Tsuruoka, Song-Ju Kim, Masakazu Aono International Center for Materials Nanoarchitectonics (WPI-MANA) National Institute for Materials Science (NIMS) 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan Phone: +81-29860-4383 E-mail: TERABE.Kazuya@nims.go.jp 1. Introduction A great number of electronics devices are used in the information and communication equipment, and upgrading of the equipment largely depends on improving the performance of semiconductor devices, which are operated by controlling the migration of electron and hole within semiconductors. It is noted that the fine processing size for conventional semiconductor devices has been decreasing year by year. However, it is feared that not only the limits to conventional fine processing technology but also the physical operating limits of semiconductor devices are being reached in near future. One possible way to overcome these technological and physical limits is to achieve breakthroughs in device materials and device-operation principle using nanotechnology. A promising type of such advanced nano-devices is the nano-ionic device based on solid state ionics and nano-technology, which is operated by controlling the local migration of ion/vacancy and electrochemical reaction instead of the migration of the electron and hole. Nano-ionic devices can be expected high performance and novel functionality which are not obtained by conventional semiconductor devices. For the reasons stated above, recently, nano-ionic devices have been drawing renewed attention as advanced nano-devices for information and communication applications operating on the basis of a new principle. In this presentation, based on the results of our research [1,2] , several developments of nano-ionic devices that enable multiple new functions are introduced. On our experiment, the local ion migration and electrochemical reaction at hetero-interfaces are controlled on a nano-scale level and even an atomic-scale level. Furthermore, the unique physical and chemical phenomena and functions caused by these controlling in order to fabricate novel nano-ionic devices with a variety of novel functions are obtained. 2. Nano-ionic devices with a variety of novel functions Nano-ionic devices are operated by skillfully controlling local ion migration and solid-state electrochemical reactions occurring at hetero-interface between solid-state electrolytes or mixed conductors and other materials such semiconductors. Accordingly, it is essential to develop the way to control the ion migration and solid-state electrochemical reactions at the hetero-interfaces on the nano-scale. The most-effective control method is to utilize a nano-structure called a “nano-space”. It is possible to apply nano-structures such as nano-scale films. We have fabricated a variety of two-/three-terminal nano-ionic devices with simple stacked nano-scale films fabricated by vapor deposition methods, such metallic oxide or graphene oxide/ionic conductor films, in which the migration of oxygen/hydrogen ion and redox reaction can be occurred at the hetero-interfaces by applying bias voltage. We have utilized changes in the following four hetero-interfacial characteristics in these nano-ionic devices to generate the unique functions. Schematic illustrations showing utilization of a point contact between a metallic filament and an electrode, a Schottky-like barrier at the hetero-interface between an ionic conductor and the electrode, a solid-state electric double layer at the hetero-interface between an solid electrolyte and a substrate, and an electrochemical reaction between ions in an ionic conductor and a substrate are respectively shown in Figures 1(a), (b), (c), and (d). By tuning the point contact, the Schottkey-like barrier, the electric double layer or the electrochemical reaction by using the local ion migrations at the hetero-interfaces, interesting useful electrical, magnetic and optical functions are obtained. By utilizing the in-situ hetero-interface controlling based on the solid state ionics and nano-technology (we call this Figure 1 Four utilizations for obtaining multi-functionality by controlling local ion transfers and electrochemical reactions at hetero-interfaces: (a) a point contact, (b) a Schottky-like barrier, (c) a solid-state electrical double layer, and (d) an electrochemical reaction. [2] S4-1 [Invited] Ext. Abs. the 17th International Workshop on Junction Technology 2017 ISBN: 978-4-86348-626-3