Study Of GeSe Compound-based Ovonic Threshold Switching Device

The emergence of novel nano-information devices provides effective solutions for efficient storage and information processing.However,the leakage current problems in their arrays have seriously hindered the development and application of array integration.Ovonic threshold switching device(OTS),as a feasible solution to solve the leakage current problem,is one of the strong candidates for large-scale integration with new devices.At the same time,it also has the potential for neuromorphic computing and functional circuit applications.In this paper,the research focuses on Ge Se-based OTS device.It aims to study the conduction mechanism of OTS device,establish a physical comprehensive model to guide the optimization of the device,and design new device structures based on Ge Se material to improve the device performance effectively.The main work of the thesis is as follows:In chapter 2,a compact model of ovonic threshold switch combining thermal dissipation effect is proposed.Firstly,the physical phenomenon and mechanism analysis of OTS device is described.Then,the simplified physical synthesis model combining the thermal dissipation effect is introduced to describe the energy flow between the device and the external environment.Finally,the model is proved valid.The results demonstrate that the model of ovonic threshold switch combining thermal dissipation effect is able to describe the ovonic threshold switching behavior accurately and integrally.In chapter 3,an optimization scheme of Ge Se-based OTS device is performed with the guidance of the model.Firstly,the design plan is introduced,with the goal of increasing the device reliability.Then the relationship between device performance and material and structural parameters is analyzed to selects electrode and dielectric layer materials with the guidance of the model.Finally,the design of device structure is introduced.In chapter 4,a symmetric multilayer ovonic threshold switching device with improved endurance and stability is demonstrated.Firstly,the device fabrication process is proposed.Then the structure of the fabrication is examined using SEM and TEM.Finally,the device characteristics is evaluated by semiconductor analyzer.The experimental results demonstrate that the fabricated Ge Se/Ge Se Sb Te OTS with symmetric multilayer interphase structure significantly improves the durability and stability of the device.An important reliability guarantee for the application of ovonic threshold switching devices is provided as selectors,neurons and functional circuits.