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Sol–gel derived amorphous LaNbOx films for forming-free RRAM applications

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Abstract

Sol–gel thin films of amorphous LaNbOx (LNO) were prepared to study the bipolar resistive switching (BRS) properties of Metal/LNO/ITO devices. We investigated the influences of film thickness, top electrode, annealing temperature, post-metal annealing (PMA), and bilayer structure on the resistive switching (RS) characteristics. In comparison to the as-deposited LNO thin film devices, the PMA-treated devices demonstrated better RS characteristics, with lower set/reset voltages (VSet/VReset = − 2.26V/0.9V), longer switching cycles (2466 cycles), and a > 101 Ron/Roff ratio. Furthermore, at 85 °C, the retention time exceeded 104 s, similar to the retention time at room temperature, indicating that random access memory (RRAM) may effectively function over 10 years. The improvement in RS characteristics can be attributed to the formation of an AlOx layer between the upper electrode and the insulating layer after PMA treatment, which increases the oxygen vacancy content and facilitates Al ion diffusion. The addition of a bilayer of Al was implemented to increase the thickness of AlOx, thereby improving the Ron/Roff ratio. However, this addition also degrades the RS properties of the device. Furthermore, the space charge-limited current (SCLC) conduction mechanism dominates in the high resistance state (HRS), while ohmic conduction prevails in the low resistance state (LRS) of the devices.

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The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.

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Acknowledgements

The work was financially sponsored by the National Science and Technology Council of Taiwan under the projects MOST 110-2221-E-006-032-MY2 and MOST 111-2221-E-006-164-MY2. The authors would like to thank Ms. Hui–Jung Shih, The Instrument Center of National Cheng Kung University for supporting the use of high-resolution SEM (Hitachi SU8000). The authors also gratefully acknowledge the use of D8 Discover equipment belonging to the Instrument Center of National Cheng Kung University.

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  1. Department of Electrical Engineering, National Cheng Kung University, Tainan City, Taiwan

    Jing-Han Wang, I.-Chun Ling, Tsung-Hsien Hsu & Cheng-Liang Huang

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Contributions

Jing-Han Wang: Conceptualization, Methodology, Investigation. I-Chun Ling: Validation, Data Curation, Investigation. Tsung-Hsien Hsu: Validation, Data Curation, Investigation. Cheng-Liang Huang: Writing—Original Draft, Supervision.

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Wang, JH., Ling, IC., Hsu, TH. et al. Sol–gel derived amorphous LaNbOx films for forming-free RRAM applications. Appl. Phys. A 130, 261 (2024). https://doi.org/10.1007/s00339-024-07438-2

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