In an article published in the journal Scientific Reports, researchers investigated and demonstrated the volatile and non-volatile switching behaviors of inkjet-printed Indium-Gallium-Zinc Oxide (IGZO) memristors at low voltages, showcasing the controllability over memory windows and switching voltages based on the thickness of the IGZO layer.
![(a) 1100 pulse stream with the optimized parameters: for the state 1 it was applied a − 0.65 V pulse for 0.1 ms; the state 0 is 1 ms after the last “1” pulse; the reading was performed at 0.05 V for 1 ms. (b) Influence of the pulse length for the “1” state (0.1 ms, 0.5 ms and 0.01 ms) using a [1100] pulse stream. (c) Influence of the pulse amplitude for the “1” state (− 0.35 V, − 0.5 V and − 0.65 V) using a [1100] pulse stream (d) Read current for various pulse streams using the “1” and “0” pulse parameters in a). https://www.nature.com/articles/s41598-024-58228-y](https://dq8l4o3au0fto.cloudfront.net/images/news/ImageForNews_3371_17126825457232068.jpg "(a) 1100 pulse stream with the optimized parameters: for the state 1 it was applied a − 0.65 V pulse for 0.1 ms; the state 0 is 1 ms after the last “1” pulse; the reading was performed at 0.05 V for 1 ms. (b) Influence of the pulse length for the “1” state (0.1 ms, 0.5 ms and 0.01 ms) using a [1100] pulse stream. (c) Influence of the pulse amplitude for the “1” state (− 0.35 V, − 0.5 V and − 0.65 V) using a [1100] pulse stream (d) Read current for various pulse streams using the “1” and “0” pulse parameters in a). https://www.nature.com/articles/s41598-024-58228-y")
(a) 1100 pulse stream with the optimized parameters: for the state 1 it was applied a − 0.65 V pulse for 0.1 ms; the state 0 is 1 ms after the last “1” pulse; the reading was performed at 0.05 V for 1 ms. (b) Influence of the pulse length for the “1” state (0.1 ms, 0.5 ms and 0.01 ms) using a [1100] pulse stream. (c) Influence of the pulse amplitude for the “1” state (− 0.35 V, − 0.5 V and − 0.65 V) using a [1100] pulse stream (d) Read current for various pulse streams using the “1” and “0” pulse parameters in a). Image Credit: https://www.nature.com/articles/s41598-024-58228-y
Background
Memristors are pivotal components in the realm of neuromorphic computing, as they offer high memory capabilities and hold the potential for facilitating efficient artificial intelligence processing. The distinctive resistive switching properties of IGZO make it a promising material for memristor applications.
Inkjet printing, known for its eco-friendliness and cost-effectiveness, presents an advantageous method for the precise deposition of thin films. By leveraging these innovative technologies, researchers and engineers can explore new frontiers in computing, harnessing the power of memristors and materials like IGZO to create advanced systems capable of tackling complex tasks with greater efficiency and accuracy.
Integrating inkjet printing with memristor technology not only streamlines manufacturing processes but also opens doors to novel applications across various fields, from artificial intelligence and machine learning to robotics and biomedical devices, paving the way for transformative advancements in technology and society.
About the Research
In the present paper, the authors focused on creating printed memristors using IGZO and investigated their characteristics in terms of memory window and switching voltages, which are influenced by the thickness of the IGZO layer. Moreover, they explored the volatile and non-volatile switching behaviors of these devices at low voltages, with a specific emphasis on their potential applications in temporal signal processing.
The study delved into the concept of printed memristors and their significance in the field of electronics. Memristors are a type of electronic device that can store and process information by changing their resistance based on the applied voltage.
Printed memristors, in particular, are fabricated using inkjet printing techniques, which offer advantages such as scalability, cost-effectiveness, and minimal material waste. The use of IGZO as the semiconductor material in these printed memristors is of particular interest due to its promising resistive switching properties.
The researchers focused on the influence of IGZO thickness on the resistive switching characteristics of the printed memristors. They optimized the printing process to achieve a good quality IGZO layer while minimizing material consumption. Additionally, they investigated how variations in the thickness of the IGZO layer affect the memory window and switching voltages of the devices.
The memory window refers to the range of resistance values that the memristor can achieve, while the switching voltages determine the voltage levels required to change the device's resistance state.
Research Findings
The outcomes showed that the printed IGZO memristors exhibited both volatile and non-volatile switching behaviors based on the programming schemes utilized. The non-volatile response followed an 8w switching polarity, with a SET voltage exceeding 2 V and a RESET voltage below -5 V. The device showcased low cycle variability and retention up to 105 s, indicating its stability and reliability. The memory window could reach up to 100, further emphasizing the potential of these devices for information storage and processing.
Furthermore, the authors provided insights into the charge transport mechanism in the printed IGZO memristors. They observed that the low resistance state (LRS) charge transport was managed by variable range hopping, suggesting defects in the IGZO layer. These defects were related to the silver ions diffusion in the form of filaments. Whereas the volatile switching mode followed an 8w scheme with an exceptionally low threshold voltage and fast switching times lower than 1 ms. The volatile properties of the memristors offered short-term retention with a time constant of 0.75 ms.
Additionally, the paper highlighted the potential applications of these printed IGZO memristors in temporal signal processing. The combination of volatile and non-volatile switching behaviors, along with their low-cost fabrication process, makes them suitable for designing efficient and simple memristive architectures based on IGZO.
The authors suggest that these devices can be integrated into readout neural networks for processing volatile signals while utilizing the non-volatile mode for long-term storage. The integration of IGZO in memristor technology not only promises cost-effectiveness but also paves the way for environmentally friendly electronic solutions. The precise control over switching properties offered by inkjet printing further underscores the potential for creating tailored electronic circuits for diverse applications.
Conclusion
In summary, the research on inkjet printed IGZO memristors highlighted a significant advancement in memristor technology and illustrated the feasibility of utilizing IGZO for various switching applications. Moving forward, the researchers acknowledged limitations and challenges, including constraints in achieving high-density memory arrays, difficulties in maintaining consistent switching characteristics across a large number of devices, and potential issues concerning the long-term stability and reliability of the memristors.
They suggested investigating innovative fabrication techniques to improve scalability and enable higher-density memory arrays, delving into optimizing device design and materials to ensure uniform and stable switching characteristics, and exploring methods to enhance the long-term stability and reliability of IGZO memristors for extended utilization in electronic applications.
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