Development of a molecular gap-type atomic switch and its stochastic operation

Abstract

The gap-type atomic switch is a novel neuromorphic device that possesses functions such as analog changes in resistance and short-term/long-term memory-based learning. However, it is difficult to integrate conventional gap-type atomic switches that use a vacuum gap and Ag2+δS, which has restricted their practical use. In this study, we developed a new, easy to fabricate gap-type atomic switch that incorporates a molecular layer as a gap and Ta2O5 as an ionic transfer material. This molecular gap-type atomic switch operates in a manner that is similar to conventional vacuum gap-type atomic switches. We also demonstrate stochastic operations using the aforementioned molecular gap-type atomic switches. These results indicate a higher potential for the practical use of gap-type atomic switches.

In-materio reservoir working at low frequencies in a Ag2S-island network

“…For instance, PSD analysis on a network of Ag nanowires coated with polyvinilpirrolydone (PVP) revealed the existence of two mechanisms that cause switching; one being low-frequency switching due to changes in connectivity across domains, and the other high-frequency switching due to Ag filament growth in the PVP film at individual junctions. 49…”

“…For instance, PSD analysis on a network of Ag nanowires coated with polyvinilpirrolydone (PVP) revealed the existence of two mechanisms that cause switching; one being lowfrequency switching due to changes in connectivity across domains, and the other high-frequency switching due to Ag filament growth in the PVP film at individual junctions. 49 In this study, the PSD of a Ag 2 S-island network was measured by applying a constant voltage of 4 V between two electrodes at opposite sites, the result of which measurement is shown in Fig. 5.…”

“…Actually, stochasticity in Ag filament growth was observed in a single device. 49 By reducing the number of Ag 2 S islands between electrodes, stochasticity could be more visible for utilization in a reservoir computing. In order to eliminate the effect, the number of Ag 2 S islands between electrodes should be larger.…”

Time‐Dependent Operations in Molecular Gap Atomic Switches

“…Chemically active sulfides such as Ag 2+δ S and Cu 2‐δ S are not suitable for integrating with CMOS (complementary metal oxide semiconductor) devices, which devices will be used together in future time‐dependent AI systems. We recently solved this issue by employing a stack of Ta 2 O 5 /Ag as a solid electrolyte electrode instead of a Ag 2+δ S/Ag stack . In this section, we report the development in detail and in the next section we describe the time‐dependent operations.…”

“…We recently solved this issue by employing a stack of Ta 2 O 5 /Ag as a solid electrolyte electrode instead of a Ag 2þδ S/Ag stack. [16] In this section, we report the development in detail and in the next section we describe the time-dependent operations. Ta 2 O 5 has also been used as an ionic transfer layer in gapless-type atomic switches because it enables easier diffusion of Ag þ cations but suppresses the diffusion of oxygen vacancies.…”