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为了改善HfO2的阻变特性, 提高氧空位(VO)导电细丝形成的一致性和均匀性, 采用基于密度泛函理论的第一性原理计算方法研究了掺杂Al的HfO2阻变材料的微观特性. 结果表明, 间隙Al (Int-Al)更适合掺入到HfO2中, 并且Int-Al与VO相对位置越近, 阻变材料趋于稳定的收敛速度越快, 形成能越小. 不同Int-Al浓度对含有VO缺陷的HfO2超胞的影响结果显示, 当掺杂Int-Al浓度为4.04%时, 分波电荷态密度图能够形成相对较好的电荷通道, 最大等势面和临界等势面值均为最高, 有利于改善HfO2阻变材料中导电细丝形成的一致性和均匀性; 形成能计算结果显示, 当Int-Al浓度低于4.04%时形成能变化缓慢, 当高于4.04%时则异常增大, 表明缺陷体系随Int-Al浓度增大越来越难以形成; 进一步研究掺杂Int-Al浓度为4.04%时晶格结构的变化, 结果显示缺陷形成能显著降低, 有利于形成完美的导电通道. 该研究为改善基于HfO2阻变存储材料的性能有一定的借鉴意义.In order to improve the resistance properties of HfO2 and increase the consistency and uniformity of conductive filaments formed by oxygen vacancies (VO), the first-principles calculation method based on density functional theory is used to study the micro-properties of Al-doped HfO2 resistive materials. The results show that the interval Al (Int-Al) is more suitable for being incorporated into HfO2, and the closer to the relative position of VO the Int-Al, the faster the convergence rate of the resistive material tends to be stable, and the smaller the formation energy. The effects of different Int-Al concentrations on the formation of HfO2 supercells with VO defects show that when the concentration of doped Int-Al is 4.04%, the fractional charge state density map can form relatively good charge channels. The maximum and critical equipotential surface values are highest, which is conducive to improving the consistency and uniformity of the formation of conductive filaments in HfO2 resistive materials. The calculation of energy formation shows that the change is slow when the concentration of Int-Al is lower than 4.04%. When the concentration of Int-Al is higher than 4.04%, the abnormal increase occurs, which indicates that the defect system becomes more and more difficult to form with the increase of the concentration of Int-Al.The introduction of the impurity and the VO defect destroy the original complete crystal structure, which causes the position of the atoms around the impurity to shift, and the valence electron orbit and the energy level of the crystal are changed, and the distribution of the internal charges of the HfO2 defect system is affected. In order to study the effect of the change of the lattice structure on the formation of the VO conductive filament, the VASP software package is used to calculate the relative ratio of the atoms in the lattice structure of the HfO2 defect system as the reference and the relative ratio of the HfO2 defect system after the optimizing the lattice structure. Further study of the change of lattice structure, when the concentration of doped Int-Al is 4.04%, shows that the defect formation energy decreases significantly, which is conducive to the formation of perfect conductive channel. The conductive channel has a certain reference significance for improving the performance of HfO2 based resistive variable memory materials.
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Keywords:
- HfO2 /
- first principles /
- interval Al /
- lattice structure








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