Stopping Voltage-Dependent PCM and RRAM-Based Neuromorphic Characteristics of Germanium Telluride

Recently, phase change chalcogenides, such as monochalcogenides, are reported as switching materials for conduction-bridge-based memristors. However, the switching mechanism focused on the formation and rupture of an Ag filament during the SET and RESET, neglecting the contributions of the phase change phenomenon and the distribution and re-distribution of germanium vacancies defects. The different thicknesses of germanium telluride (GeTe)-based Ag/GeTe/Pt devices are investigated and the effectiveness of phase loops and defect loops future application in neuromorphic computing are explored. GeTe-based devices with thicknesses of 70, 100, and 200 nm, are fabricated and their electrical characteristics are investigated. Highly reproducible phase change and defect-based characteristics for a 100 nm-thick GeTe device are obtained. However, 70 and 200 nm-thick devices are unfavorable for the reliable memory characteristics. Upon further analysis of the Ag/GeTe/Pt device with 100 nm of GeTe, it is discovered that a state-of-the-art dependency of phase loops and defect loops exists on the starting and stopping voltage sweeps applied on the top Ag electrode. These findings allow for a deeper understanding of the switching mechanism of monochalcogenide-based conduction-bridge memristors.

Automated summary

Recently, phase change chalcogenides, particularly monochalcogenides, have shown potential as switching materials for conduction-bridge-based memristors. However, previous studies have mainly focused on the formation and rupture of an Ag filament during the SET and RESET processes, disregarding the contributions of the phase change phenomenon and the distribution and re-distribution of germanium vacancies defects. In this study, GeTe-based devices with different thicknesses were investigated, revealing the effectiveness of phase loops and defect loops for future applications in neuromorphic computing. The electrical characteristics of the devices were examined, and it was found that a 100 nm-thick GeTe device exhibited highly reproducible phase change and defect-based characteristics, while 70 nm and 200 nm-thick devices were not suitable for reliable memory performance. Further analysis of the 100 nm-thick GeTe device revealed a state-of-the-art dependency of phase loops and defect loops on the starting and stopping voltage sweeps applied on the top Ag electrode, providing a deeper understanding of the switching mechanism of monochalcogenide-based conduction-bridge memristors.