Forming-free, bi-directional polarity conductive-bridge memory devices with Ge2Sb2Te5 solid-state electrolyte and Ag active electrode

Abstract

Preparation and characteristics of conductive-bridge random access memory devices containing Ge2Sb2Te5 (GST) chalcogenide as the solid-state electrolyte, Ag as the active electrode, and W-Ti as the counter electrode are presented. As revealed by the electrical measurement, only the samples containing crystalline GST exhibited the resistive switching behaviors. With an insertion of ZnS-SiO2 dielectric layer at the Ag/GST interface and a postannealing at 100 °C for 1 min, the sample exhibited the best electrical performance with satisfactory cycleability and retention properties. Moreover, the forming-free and bi-directional polarity features were observed in such a sample type. Microstructure and composition analyses found the finely dispersed nano-scale Ag clusters in GST and, when electrical bias is applied, the migrating Ag ions may build up the connections in between neighboring Ag clusters. Moreover, grain boundaries in polycrystalline GST might be the main paths for Ag migration. The thread-like conduction channels in GST hence form, leading to the low resistance state of sample. On the contrary, the depletion of Ag in GST broke the connections in between Ag clusters when the electrical bias is reversed. This led to the rupture of conduction channels and, hence, the high resistance state of sample. The low operational voltage, forming-free, and bi-directional polarity features observed in (AZGW)T sample might also originated from the fine dispersion of Ag clusters in GST electrolyte.

Electrodeposition of GeSbTe-Based Resistive Switching Memory in Crossbar Arrays

“…This promising prospect has stimulated a significant amount of effort to investigate the resistive switching behavior of chalcogenide materials . Several chalcogenide alloys including GeSbTe, ,− AgGeSe, AgGeTe, and AgInSbTe have been reported to demonstrate the resistive switching behavior. In most cases, the resistive switching effects observed in chalcogenide materials are induced by connecting and breaking the CFs from the migration of metal cations (e.g., Cu and Ag) provided by active (oxidizable) electrodes, ,− ,,, which is also known as the electrochemical metallization (ECM) process.…”

“…Several chalcogenide alloys including GeSbTe, ,− AgGeSe, AgGeTe, and AgInSbTe have been reported to demonstrate the resistive switching behavior. In most cases, the resistive switching effects observed in chalcogenide materials are induced by connecting and breaking the CFs from the migration of metal cations (e.g., Cu and Ag) provided by active (oxidizable) electrodes, ,− ,,, which is also known as the electrochemical metallization (ECM) process. This process, which requires adoption of Ag or Cu as the active metallic element, could pose a problem with contamination control in mass-production lines for semiconductor device fabrication .…”

Reliable Ge2Sb2Te5‐Integrated High‐Density Nanoscale Conductive Bridge Random Access Memory using Facile Nitrogen‐Doping Strategy

“…It is a desirable material for realization of eNVMs and CBRAMs owing to its high crystallization speed, fast ionic movement, nanoscale CFs, phase stability, reversible switchability, high data retention for both phases under ambient condition, and low power consumption . GST has been studied as SE, switching layer, thermoelectric heater, and thermal barrier in CBRAMs with a reasonable memory characteristics. Although GST has more beneficial characteristics than other chalcogenides for a reliable CBRAM, its performance must be improved by elevating the crystallization temperature.…”

A new opportunity for the emerging tellurium semiconductor: resistive switching device implementation

“…Actually, PCMs have often been utilized as the dielectric layer in EC-RS devices but most of these devices used electrochemically active Ag or Cu electrodes. [71][72][73][74] Recently, the use of Te electrodes was also found to enable RS [59][60][61][62][63][64] in which the formation of local conducting filaments led to HR-to-LR transition while the rupture of filaments led to the reverse transition. In order to confirm whether the RS phenomenon for our Te/Sb2Te3/Te devices was based on such process, we measured the electrode area dependent HRs and LRs of the device in the NV-RS (under 500 μA CC) and V-RS (under 1.5 mA CC) modes, respectively.…”