Graduate School of Information Science and Technology, Hokkaido University , Sapporo, Hokkaido 060-0814, Japan.
ACS Appl Mater Interfaces. 2018 Feb 14;10(6):5609-5617. doi: 10.1021/acsami.7b15384. Epub 2018 Feb 1.
We demonstrate that the inclusion of a Ta interfacial layer is a remarkably effective strategy for forming interfacial oxygen defects at metal/oxide junctions. The insertion of an interfacial layer of a reactive metal, that is, a "scavenging" layer, has been recently proposed as a way to create a high concentration of oxygen defects at an interface in redox-based resistive switching devices, and growing interest has been given to the underlying mechanism. Through structural and chemical analyses of Pt/metal/SrTiO/Pt structures, we reveal that the rate and amount of oxygen scavenging are not directly determined by the formation free energies in the oxidation reactions of the scavenging metal and unveil the important roles of oxygen diffusibility. Active oxygen scavenging and highly uniform oxidation via scavenging are revealed for a Ta interfacial layer with high oxygen diffusibility. In addition, the Ta scavenging layer is shown to exhibit a highly uniform structure and to form a very flat interface with SrTiO, which are advantageous for the fabrication of a steep metal/oxide contact.
我们证明了在金属/氧化物结处形成界面氧缺陷的一种非常有效的策略是包含 Ta 界面层。最近提出了在氧化还原型电阻开关器件中在界面处形成高浓度氧缺陷的一种方法，即在界面层插入反应性金属，即“清除”层，并且对其潜在机制的研究产生了浓厚的兴趣。通过对 Pt/金属/SrTiO/Pt 结构的结构和化学分析，我们揭示了氧清除的速率和数量并不是直接由清除金属的氧化反应的形成自由能决定的，并揭示了氧扩散性的重要作用。具有高氧扩散性的 Ta 界面层可以实现主动氧清除和通过清除实现高度均匀的氧化。此外，证明 Ta 清除层具有高度均匀的结构并且与 SrTiO 形成非常平坦的界面，这有利于制造陡峭的金属/氧化物接触。
