Oxygen vacancy effects in HfO2-based resistive switching memory: First principle study

Abstract

The work investigated the shape and orientation of oxygen vacancy clusters in HfO2-base resistive random access memory (ReRAM) by using the first-principle method based on the density functional theory. Firstly, the formation energy of different local Vo clusters was calculated in four established orientation systems. Then, the optimized orientation and charger conductor shape were identified by comparing the isosurface plots of partial charge density, formation energy, and the highest isosurface value of oxygen vacancy. The calculated results revealed that the [010] orientation was the optimal migration path of Vo, and the shape of system D4 was the best charge conductor in HfO2, which effectively influenced the SET voltage, formation voltage and the ON/OFF ratio of the device. Afterwards, the PDOS of Hf near Vo and total density of states of the system D4_010 were obtained, revealing the composition of charge conductor was oxygen vacancy instead of metal Hf. Furthermore, the migration barriers of the Vo hopping between neighboring unit cells were calculated along four different orientations. The motion was proved along [010] orientation. The optimal circulation path for Vo migration in the HfO2 super-cell was obtained.

Routes for increasing endurance and retention in HfO2 -based resistive switching memories

“…In order to provide an additional checkpoint for this hypothesis, we have calculated the energy barrier for oxygen migration through the one-dimensional channels of I bam-Hf 2 O 3 , which amounts to 0.51 eV (see Table III). This barrier is significantly lower than both that for the migration of a neutral oxygen vacancy in the monoclinic HfO 2 (∼2.5 eV) [58] and even that of a positively charged vacancy (∼0.7 eV, Ref. [59]).…”

Au doping effects in ZrO<sub>2</sub>-based resistance random access memory based on first-principles calculations

“…了氧空位迁移势垒能(E m ). 迁移势垒能的大小与氧空 位迁移的难易程度相关, 进而影响到RRAM器件的置 位(set)电压的大小 [39,40] . 图5(a)和(b)分别为未掺杂和 [41] :…”

Analysis of Oxygen and Nitrogen Redistribution at Interfaces of HfO2 with Laminate TiN/TiAl/TiN Electrodes

“…Redistribution of light atoms (O, N) is the key factor determining electrical properties of oxide-based insulators (O vacancies account for resistive switching − ), semiconductors (O vacancies − and N vacancies − determine doping of semiconducting compounds), and conductors (p-type conduction of NiO). As one of the factors determining redistribution of light atoms (O, N), one can discern chemical interaction of oxides with electrode materials such as TiN.…”