基于蒙特卡洛方法的钛氧化物忆阻器辐射损伤研究

纳米钛氧化物忆阻器有望成为新一代阻性存储器基本单元并应用于辐射环境中的航天器控制及数据存储系统. 辐射能量, 强度, 方向, 持续时间等要素发生改变均可能对钛氧化物忆阻器受到的辐射损伤构成影响, 然而, 目前尚无相关具体研究. 基于以蒙特卡洛方法为核心的SRIM仿真, 本文针对宇宙射线主体组成部分——质子及 α射线定量研究了各个辐射要素与钛氧化物忆阻器辐射损伤的关联, 依据器件实测数据研究了辐射要素与导通阻抗, 截止阻抗及氧空缺迁移率等忆阻器主要参数的关系, 进一步利用SPICE仿真讨论了辐射对杂质漂移与隧道势垒共存特性的影响, 从而为评估及降低钛氧化物忆阻器辐射损伤, 提高器件应用于辐射环境的可靠性提供依据.

Research on radiation damage in titanium oxide memristors by Monte Carlo method

Nano titanium oxide memristor is expected to be the basic cell of a new generation of resistive memory and applied in the control and data storage systems of spacecrafts that work in a radiation environment. The changes of radiation key factors, such as energy, intensity, direction, and duration etc. probably have an influence on the radiation damage of the titanium oxide memristor. However, there has been no relatively detailed research of it. Based on the SRIM simulation, with the Monte Carlo method used as its core, the main part of cosmic rays——proton and alpha rays and the relevance between the key factors and radiation damage in titanium oxide memristor are quantitatively studied. According to the experimental data, the relations between key factors and R_{ON}, R_{OFF}, the mobility of oxygen vacancies are analyzed. We find that the mobility of oxygen vacancies increases abruptly when the ratio between oxygen vacancies and titanium oxide molecules is greater than 0.16. Moreover, compared with proton radiation, the alpha particle radiation going into the active region in titanium oxide memristor, especially at an oblique incidence angle may cause a greater damage to the device and should be strictly avoided, and the radiation damage increases as the intensity and duration of the radiation are raised. SPICE simulations are further utilized to show the influence of radiation on the characteristics of the coexistence of dopant drift and the tunnel barrier. We also find that the titanium oxide memristor device will gradually turn into a normal resistor with a low resistance and lose its charge-memory ability after persistent radiations. This work provides support for evaluating and reducing radiation damage for titanium oxide memristors, so as to improve the reliability of the device in radiation environment.