CNR--Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), via P. Gobetti 101, I-40129 Bologna, Italy.
Nanoscale. 2013 May 7;5(9):3954-60. doi: 10.1039/c3nr00106g. Epub 2013 Mar 28.
We have investigated the role of the electroforming process in the establishment of resistive switching behaviour for Pt/Ti/Pr0.5Ca0.5MnO3/SrRuO3 layered heterostructures (Pt/Ti/PCMO/SRO) acting as non-volatile Resistance Random Access Memories (RRAMs). Electron spectroscopy measurements demonstrate that the higher resistance state resulting from electroforming of as-prepared devices is strictly correlated with the oxidation of the top electrode Ti layer through field-induced electromigration of oxygen ions. Conversely, PCMO exhibits oxygen depletion and downward change of the chemical potential for both resistive states. Impedance spectroscopy analysis, supported by the detailed knowledge of these effects, provides an accurate model description of the device resistive behaviour. The main contributions to the change of resistance from the as-prepared (low resistance) to the electroformed (high resistance) states are respectively due to reduced PCMO at the boundary with the Ti electrode and to the formation of an anisotropic n-p junction between the Ti and the PCMO layers.
我们研究了电成型过程在 Pt/Ti/Pr0.5Ca0.5MnO3/SrRuO3 分层异质结构（Pt/Ti/PCMO/SRO）中建立电阻开关行为中的作用，该异质结构可用作非易失性电阻随机存取存储器（RRAMs）。电子能谱测量表明，通过电场诱导氧离子的迁移，电成型制备的器件中较高的电阻状态与顶部电极 Ti 层的氧化密切相关。相反，PCMO 在两个电阻状态下都表现出氧损耗和化学势的下降。阻抗谱分析，结合这些效应的详细知识，为器件的电阻行为提供了一个准确的模型描述。从初始（低电阻）状态到电成型（高电阻）状态的电阻变化的主要贡献分别是由于与 Ti 电极交界处的 PCMO 减少，以及 Ti 和 PCMO 层之间形成各向异性的 n-p 结。
