This study examines resistive switching in a Cu/ZnO/ITO structure, uncovering an anomalous phenomenon that provides insights into the mechanisms of parallel conducting filaments in ZnO thin films. The current–voltage (I–V) characteristics exhibit a sharp switch at a positive threshold voltage around 2 V, transitioning from a high resistance pristine state to a low resistance state, interpreted as the formation of a Cu filament via electrochemical metallization. However, after this forming process, the device remains in the low resistance state and cannot reset to a high resistance state in either polarity of the applied voltage, suggesting the presence of a strong, unbreakable Cu filament after the forming process. What makes this phenomenon anomalous is the observed weak bipolar resistive switching in the cycles following the forming cycle, despite the presence of the Cu filament. The I–V characteristics of forward- and reverse-bias sweeps suggest that the weak bipolar resistive switching results from an additional filament formed in parallel with the existing unbreakable Cu filament. Using a parallel conducting filaments model, the resistivity of this additional filament is calculated to be ∼10−7–10−5 Ω m, indicating that this filament is likely generated by oxygen vacancies rather than metal atoms in the ZnO films.

中文翻译：

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电阻开关 ZnO 薄膜中的并联导电丝


这项研究检查了 Cu/ZnO/ITO 结构中的电阻切换，揭示了一种异常现象，为了解 ZnO 薄膜中平行导电丝的机制提供了见解。电流-电压 (I-V) 特性在 2 V 左右的正阈值电压下表现出急剧的切换，从高电阻原始状态转变为低电阻状态，这被解释为通过电化学金属化形成铜丝。然而，在此形成过程之后，该器件保持在低电阻状态，并且在所施加电压的任一极性下都不能重置为高电阻状态，这表明在形成过程之后存在坚固的、牢不可破的铜丝。使这种现象异常的是，尽管存在铜丝，但在成形周期之后的周期中观察到弱双极电阻切换。正向和反向偏置扫描的 I-V 特性表明，弱双极电阻开关是由与现有的牢不可破的铜丝平行形成的附加丝引起的。使用平行导电丝模型，计算出该附加丝的电阻率为∼10−7–10−5 Ω m，表明该丝可能是由氧空位而不是ZnO薄膜中的金属原子产生的。