GeS conducting-bridge resistive memory device with IGZO buffer layer for highly uniform and repeatable switching

Abstract

A double stacked monochalcogenide GeS-based conducting-bridge random access memory (CBRAM) device with a IGZO buffer layer is investigated for highly improved resistive memory characteristics. The IGZO/GeS double layer is found to provide the CBRAM with a markedly improved sub-1V DC set/reset-voltage distributions (<±0.1 V variation). High endurance (>107 cycles) and retention (>105 s at 85 °C) performance are also achieved. The metal ion diffusion and migration rates in the solid electrolytes along with the redox reaction rates at the electrodes determine the respective resistive switching (RS) mechanism in the CBRAM device. Considering this fact, it is proposed that Ag diffusion into IGZO creates a virtual electrode, when coupled with strong ionic transport in GeS, consistently mediate the formation/dissolution of Ag filament there, thus reducing switching variation. Understanding the RS mechanism based on the materials' physical and chemical properties and tailoring the device structure allow an optimal control over cycle to cycle and device to device variability. The findings show that this material combination or similar oxide/chalcogenide stacks may offer a facile means for mitigating CBRAM variability.