Quantum Mechanical Simulation of Defect Migration and Phase Transition Dynamics Unterlying Resistive Switching in TiO2

忆阻器是无源电子元件，其欧姆电阻可以通过外部施加的电流在不同的稳定状态之间切换。由于这些状态保持稳定，即使外部电流被切断，忆阻器也特别适合于替代闪存单元用作非易失性存储器。电阻式随机存取存储器（RRAM）存储器单元将比复杂的基于晶体管的闪速存储器便宜得多且更小。然而，技术上相关的氧化物材料的忆阻行为的微观机制迄今为止还没有得到足够好的理解，以允许基于知识的工程。RRAM器件的改进受到对阻变机制缺乏基本理解的阻碍。实验数据表明，在由缺氧氧化物材料制造的忆阻器中，形成并溶解了导电细丝，这与缺氧相关缺陷的迁移有关。在具有特殊技术意义的TiO 2中，氧原子和空位的迁移被认为是至关重要的。在拟议的项目中，在外部电场和温度梯度的驱动力下，TiO2中点缺陷迁移动力学的原子分辨量子模拟将与TiO2−x中氧空位有序化的动态模拟一起进行。应开发缺氧TiO 2中阻变机制的经验模型，以实现基于知识的RRAM工程。

Memristors are passive electronic elements, the ohmic resistance of which can be switched between different stable states by an externally applied current. Because these states remain stable, even if the external current is switched off, memristors are especially suitable to replace flash memory cells for use as nonvolatile memory. Resistive random access memory (RRAM) memory cells would be significantly cheaper and smaller than complex, transistor based flash memory. However, the microscopic mechanisms underlying the memristive behavior of technically relevant oxide materials are so far not understood well enough to allow knowledge-based engineering. The improvement of RRAM devices is hindered by a lack of basic understanding of the resistive switching mechanism. Experimental data indicate that in memristors manufactured from oxygen deficient oxide materials, conducing filaments are formed and dissolved, connected to the migration of oxygen deficiency related defects. In TiO2, which is of particular technological interest, the migration of oxygen atoms and vacancies is assumed to be of crucial importance. In the proposed project, atomically resolved quantum simulations of the dynamics of point defect migration in TiO2 under the driving forces of external electric field and temperature gradients shall be pursued together with dynamic simulations of oxygen vacancy ordering in TiO2−x. An empirical model of the resistive switching mechanism in oxygen deficient TiO2 shall be developed to enable knowledge based RRAM engineering.