The modulation of Schottky barrier height (SBH) due to defect migration has been suggested to be an important driving mechanism for resistive switching in metal–oxide–metal structures. Here, we explore the SBH and its modulation due to different interface structures and defects in the Pt|MgO|Pt(001) system using hybrid Heyd–Scuseria–Ernzerhof density functional theory. The computed magnitudes of SBH at Pt|MgO interfaces obtained using the generalized gradient approximation (local density approximation) functional are found to be significantly underestimated as compared to those obtained using hybrid functional. Furthermore, the magnitudes of SBH are found to depend critically on interface structures. In the case of defect-free Pt|MgO interfaces, the p-type SBH is found to be 4.13 eV and 3.04 eV for interfaces having adjacent Pt–O and Pt–Mg bonds, respectively. In addition, the SBH magnitudes are found to exhibit significant variation primarily due to nominal effective charges on interface layers which, in turn, are induced by interface defects such as O and Mg vacancies. The magnitudes of p-type SBH are found to increase (decrease) by ∼1.0–1.5 eV as the ionic layers with charge +1e (−1e) are introduced at the interface. The modulation in SBH due to interface ionic/polar layer is explained using a micro-capacitor model. Furthermore, the SBH is found to shift by ∼0.2 eV with the varying distance of O and/or Mg vacancies from the interface. Our results suggest that fluctuations in experimental resistive switching data in Pt|MgO structures may originate due to fluctuations in SBH induced by changes in interface atomic structure. The study also shows that SBH in Pt|MgO and related structures may be modulated in a controlled way by the insertion of interface polar layers. The lower and upper bounds of the SBH magnitudes are also estimated using a semi-empirical model expressed in terms of parameters such as charge neutrality level, ionization potential, pinning parameter, and metal work function. The quantitative results on the SBH modulation presented in the study may be expected to have important implications for resistive switching phenomenon in Pt|MgO and similar other structures.

中文翻译：

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由于 Pt|MgO|Pt 异质结中的界面结构和缺陷导致的肖特基势垒高度和调制对电阻开关的影响

由于缺陷迁移引起的肖特基势垒高度（SBH）的调制已被认为是金属-氧化物-金属结构电阻转换的重要驱动机制。在这里，我们使用混合 Heyd-Scuseria-Ernzerhof 密度泛函理论探索由于 Pt|MgO|Pt(001) 系统中不同的界面结构和缺陷导致的 SBH 及其调制。与使用混合函数获得的那些相比，使用广义梯度近似（局部密度近似）函数获得的 Pt|MgO 界面处的 SBH 计算量被发现显着低估。此外，发现 SBH 的大小严重依赖于界面结构。在无缺陷 Pt|MgO 界面的情况下，发现具有相邻 Pt-O 和 Pt-Mg 键的界面的 p 型 SBH 为 4.13 eV 和 3.04 eV，分别。此外，发现 SBH 大小表现出显着变化，主要是由于界面层上的标称有效电荷，而这又是由界面缺陷（例如 O 和 Mg 空位）引起的。发现 p 型 SBH 的大小增加（减少）~1.0-1.5 eV，因为在界面处引入了具有 +1e (-1e) 电荷的离子层。使用微电容器模型解释由于界面离子/极性层而导致的 SBH 调制。此外，发现 SBH 随 O 和/或 Mg 空位距界面的距离变化而移动~0.2 eV。我们的结果表明，Pt|MgO 结构中实验电阻切换数据的波动可能源于界面原子结构变化引起的 SBH 波动。该研究还表明，可以通过插入界面极性层以受控方式调节 Pt|MgO 和相关结构中的 SBH。SBH 量级的下限和上限也使用半经验模型估计，该模型以电荷中性水平、电离电位、钉扎参数和金属功函数等参数表示。研究中提出的 SBH 调制的定量结果可能对 Pt|MgO 和类似其他结构中的电阻转换现象具有重要意义。和金属功函数。研究中提出的 SBH 调制的定量结果可能对 Pt|MgO 和类似其他结构中的电阻转换现象具有重要意义。和金属功函数。研究中提出的 SBH 调制的定量结果可能对 Pt|MgO 和类似其他结构中的电阻转换现象具有重要意义。