Optimal migration path of Ag in HfO2： A first-principles study
摘要
First-principles calculations are used to investigate the migration path of Ag in the Hf O2-based resistive random access memory(Re RAM). The formation energy calculation suggests that there are two different sites(site 1 and site 3) for the incorporation of Ag atoms into the Hf O2 unit cell. Thermodynamic analysis shows that the motion of Ag atom in the Hf O2 supercell appears to be anisotropic, which is due to the fact that the Ag atom at site 3 moves along the [1ˉ11] orientation,but the Ag atom at site 1 moves along the [001] orientation. The migration barriers of the Ag atoms hopping between neighboring unit cells are calculated along five different orientations. Difficulty in producing motion of the Ag atom varies with the migration barrier: this motion is minimized along [1ˉ11] orientation. Furthermore, The optimal circulation path for Ag migration within the Hf O2 supercells is obtained, and is found to be approximately along the [1ˉ11] orientation.Therefore, it is proposed that the positive voltage should be applied along this orientation, the conduction filament may form more easily, which could improve the response time and reduce the power consumption in Re RAM applications.