Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416004, India.
Computational Electronics and Nanoscience Research Laboratory, School of Nanoscience and Biotechnology, Shivaji University, Kolhapur 416004, India.
J Colloid Interface Sci. 2023 Jul 15;642:540-553. doi: 10.1016/j.jcis.2023.03.189. Epub 2023 Apr 2.
Resistive switching (RS) memories have attracted great attention as promising solutions to next-generation non-volatile memories and computing technologies because of their simple device configuration, high on/off ratio, low power consumption, fast switching, long retention, and significant cyclic stability. In this work, uniform and adherent iron tungstate (FeWO) thin films were synthesized by the spray pyrolysis method with various precursor solution volumes, and these were tested as a switching layer for the fabrication of Ag/FWO/FTO memristive devices. The detailed structural investigation was done through various analytical and physio-chemical characterizations viz. X-ray diffraction (XRD) and its Rietveld refinement, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) techniques. The results reveal the pure and single-phase FeWO compound thin film formation. Surface morphological study shows the spherical particle formation having a diameter in the range of 20 to 40 nm. The RS characteristics of the Ag/FWO/FTO memristive device demonstrate non-volatile memory characteristics with significant endurance and retention properties. Interestingly, the memory devices show stable and reproducible negative differential resistance (NDR) effects. The in-depth statistical analysis suggests the good operational uniformity of the device. Moreover, the switching voltages of the Ag/FWO/FTO memristive device were modeled using the time series analysis technique by utilizing Holt's Winter Exponential Smoothing (HWES) approach. Additionally, the device mimics bio-synaptic properties such as potentiation/depression, excitatory post-synaptic current (EPSC), and spike-timing-dependent plasticity (STDP) learning rules. For the present device, the space-charge-limited current (SCLC) and trap-controlled-SCLC effects dominated during positive and negative bias I-V characteristics, respectively. The RS mechanism dominated in the low resistance state (LRS), and the high resistance state (HRS) was explained based on the formation and rupture of conductive filament composed of Ag ions and oxygen vacancies. This work demonstrates the RS in the metal tungstate-based memristive devices and demonstrates a low-cost approach for fabricating memristive devices.
阻变（RS）存储器因其简单的器件结构、高的开关比、低功耗、快速开关、长保持时间和显著的循环稳定性，而被认为是下一代非易失性存储器和计算技术的有前途的解决方案，因此受到了极大的关注。在这项工作中，通过喷雾热解法用不同的前驱体溶液体积合成了均匀且附着的钨酸亚铁（FeWO）薄膜，并将其用作制备 Ag/FWO/FTO 忆阻器件的开关层。通过各种分析和物理化学特性的研究，如 X 射线衍射（XRD）及其 Rietveld 精修、拉曼光谱和 X 射线光电子能谱（XPS）技术，对其进行了详细的结构研究。结果表明，形成了纯单相 FeWO 化合物薄膜。表面形貌研究表明，形成了具有 20 至 40nm 直径的球形颗粒。Ag/FWO/FTO 忆阻器件的 RS 特性表现出具有显著耐久性和保持特性的非易失性存储特性。有趣的是，该忆阻器件表现出稳定且可重复的负微分电阻（NDR）效应。深入的统计分析表明该器件具有良好的操作均匀性。此外，通过利用霍尔特冬季指数平滑（HWES）方法的时间序列分析技术，对 Ag/FWO/FTO 忆阻器件的开关电压进行建模。此外，该器件模拟了生物突触特性，如增强/抑制、兴奋性突触后电流（EPSC）和尖峰时间依赖可塑性（STDP）学习规则。对于本器件，在正偏和负偏 I-V 特性中，空间电荷限制电流（SCLC）和陷阱控制 SCLC 效应分别占主导地位。在低电阻状态（LRS）中，RS 机制占主导地位，而高电阻状态（HRS）则基于 Ag 离子和氧空位组成的导电丝的形成和断裂来解释。这项工作证明了基于金属钨酸盐的忆阻器件中的 RS，并展示了一种制造忆阻器件的低成本方法。
