First principles study of effect of vaiable component Al on HfO<sub>2</sub> resistance

Abstract

<sec>In order to improve the resistance properties of HfO<sub>2</sub> 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 HfO<sub>2</sub> resistive materials. The results show that the interval Al (Int-Al) is more suitable for being incorporated into HfO<sub>2</sub>, 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 HfO<sub>2</sub> 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 HfO<sub>2</sub> 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. </sec><sec>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 HfO<sub>2</sub> 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 HfO<sub>2</sub> defect system as the reference and the relative ratio of the HfO<sub>2</sub> 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 HfO<sub>2</sub> based resistive variable memory materials.</sec>