中文摘要：

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。

英文摘要：

The resistance switching physical mechanism of the resistive random access memory （RRAM） is studied with the first-principle based on the density functional theory. The comparison calculation of the formation energies, energy band, density of states and migration barrier of the oxygen vacancy defect system and doped system （A1, Ti and La） in the monoclinic HfO2 are performed. The results show that the formation energy can be reduced significantly after doping, which indicates that doping promotes the formation of oxygen vacancies. With the existence of oxygen vacancies, the band gap width reduces obviously and a peak of the occupied state emerges in the band gap, confirming that the conductivity of the material is enhanced dramatically. The oxygen vacancy is the primary cause for the conductivity of the material while the impurity is the auxiliary factor. Furthermore, based on the analysis of the migration barrier, the oxygen vacancies form the clusters due to the interaction resulted from the metal impurities, which influences the operating voltage and the speed of the devices.