Compositional tuning of negative differential resistance in a bulk silver iodide memristor

Abstract

The electrical memory switching effect has received great interest for the development of emerging memory technology, such as memristors. High density, fast response, multi-bit storage and low power consumption are their attractive features. Among other materials, silver iodide (AgI) is emerging as a potential candidate for memory applications; it is prototype superionic conductor in which silver ions (Ag⁺) form a “liquid-like” lattice with exceptionally high ionic conductivity. It exhibits symmetrical negative differential resistance (NDR), which is a new effect for memory technology. In the case of AgI, it is poorly understood and hence an attempt has been made to understand this effect by tuning the chemical composition. Here, AgI nanoparticles are synthesized via a simple colloidal route to produce bulk memristors. The room temperature current–voltage characteristics of these devices have been studied as well as using spectroscopic techniques. The NDR effect is observed at +0.36 V and at −0.38 V with an ON/OFF ratio of 4.97 × 10² for more than 100 cycles with 99% repeatability. A new atomic model for the NDR effect in AgI is proposed.