A Better Understanding of Memory Behavior of Fast Ion Conducting AgI-Ag2O-MoO3 Glasses

Abstract

Memory behavior of fast ion conducting AgI-Ag2O-MoO3 glasses, over a wide range of compositions within the glass forming region, proportioning a balance between glass matrix former (MoO3) and glass matrix expander (AgI), has been scrutinized thoroughly to understand the switching mechanism of bulk samples with inert electrode. The ion transport, the agility to reach the threshold voltage (Vth), Vth - composition (x) profile and thickness dependence of Vth have been explained in the lights of Mott-Gurney model for electric field driven thermally activated ion hopping. A feature of alteration in memory behavior from reversible to irreversible, due to change in electrode type from active to passive has been observed and discussed. Being a decoupled system, Vth - x profile exhibits a seemingly scattered nature while glass transition temperature (Tg) - x profile is monotonically increasing, indicating growing network connectivity. Besides, these two profiles together narrow down the composition region where the most thermally stable, with minimum power loss and fast switching performing samples lie. During switching, a metallic filament forms between two electrodes. Raman and Energy dispersive X-ray spectroscopy study find no traces of molybdenum, oxygen and electrode material in the filament. Scanning electron microscopy image shows bubble formation in the vicinity of anode - electrolyte interface which is analogous to oxidation reaction but no evidence of anionic transport has been found. This in turns helps us to understand the corrosion mechanism in the glass matrix due to the electrochemical process. Overall, the focus of this research work is to understand some crucial issues regarding the memory behavior of this specific material to enable us to exploit the material for further development in the non-volatile memory technology.