Review of solid-state proton devices for neuromorphic information processing

Abstract

Abstract This is a review of proton devices for neuromorphic information processing. While solid-state devices utilizing various ions have been widely studied for non-volatile memory, the proton, which is the smallest ion, has been relatively overlooked despite its advantage of being able to move through various solids at RT. With this advantage, it should be possible to control proton kinetics not only for fast analog memory function, but also for real-time neuromorphic information processing in the same time scale as humans. Here, after briefing the neuromorphic concept and the basic proton behavior in solid-state devices, we review the proton devices that have been reported so far, classifying them according to their device structures. The benchmark clearly shows the time scales of proton relaxation ranges from several milliseconds to hundreds of seconds, and completely match the time scales for expected neuromorphic functions. The incorporation of proton degrees of freedom in electronic devices will also facilitate access to electrochemical phenomena and subsequent phase transitions, showing great promise for neuromorphic information processing in the real-time and highly interactive edge devices.