Impact of lattice plane orientation in TiO_2 based resistive switching memory: A computational approach

摘要

Resistive Random Access Memories (ReRAMs) are promising future candidates for nonvolatile memory. The underlying mechanism involves resistive switching in high-k dielectric layers, and changes in resistance due to different mechanisms are caused by the evolution of defective structures triggered by electrical and thermal effects. For the memory purpose of the ReRAM, the electrical field can be used to adjust the resistance of the resistance material for the storage of information. In this study, nonequilibrium molecular dynamics simulations with the charge equilibration method are used to study the electrochemical reactions of ReRAMs. The Cu/TiO_2/Ti heterojunction structures with (100)/(001), (100)/(110), (100)/(lll), and (100)/(120) lattice planes as grains are considered to investigate the resistive switching properties based on the electrical, thermal, and structural properties of three models. Dielectric layers with the grain boundary of the bicrystal structure are composed of titanium dioxide nanoparticles. Our results demonstrate that an applied external electric field on grain boundaries is a key issue in resistive switching. Furthermore, the simulation results were verified with the experimental data. Overall, this simulation work provides details of the fundamental mechanism of resistance switching, including variation of the atomic structure and electronic properties, at the atom length scale and picosecond timescale, which suggest a number of useful aspects for the future development and optimization of materials for this ReRAM technology.