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采用基于密度泛函理论的第一性原理对阻变随机存取存储器(RRAM)器件的阻变物理机制进行了分析研究。对比计算了氧空位缺陷或掺杂(Al,Ti和La)HfO2体系的形成能、能带结构、态密度以及迁移势垒能,结果表明,掺杂后体系的氧空位形成能明显减小,掺杂促进了氧空位的形成;无论掺杂和未掺杂的体系,当氧空位存在时禁带宽度会明显减小,且禁带中多出一个占据态的峰,材料的导电能力明显增强。表明氧空位是材料导电的主要因素,杂质起到辅助作用。计算结果与相关实验结果相符合。进一步分析迁移势垒能,说明金属杂质对氧空位产生缔合作用而促使形成团簇,从而对器件的操作电压、工作速度等产生影响。
The first principle of density functional theory (DFT) is used to analyze the resistive physical mechanism of resistive random access memory (RRAM). The formation energy, the energy band structure, the density of states and the transfer barrier energy of oxygen vacancies or doped (Al, Ti and La) HfO2 system are calculated and compared. The results show that the formation of oxygen vacancies can be significantly reduced after the doping, Doping promotes the formation of oxygen vacancies; both doped and undoped systems, when the oxygen vacancies exist, the forbidden band width will be significantly reduced, and in the forbidden band more than an occupied peak, the conductivity of the material is significantly enhanced . Oxygen vacancies show that the material is the main conductive factor, impurities play a supporting role. The calculation results are consistent with the relevant experimental results. Further analysis of the migration barrier energy shows that metal impurities have an associative effect on the oxygen vacancy and contribute to the formation of clusters that affect the device operating voltage and operating speed.