Investigation of the dynamics of NbOx-based threshold switching devices for next-generation computing and wearable electronics

• Main Author: Ang, Jia Min
• Other Authors: Lew Wen Siang
• Format: Thesis-Doctor of Philosophy
• Language: English
• Published: Nanyang Technological University 2024
• Subjects: Physics
• Online Access: https://hdl.handle.net/10356/174211
• Institution: Nanyang Technological University

As the current CMOS-based memory technologies face challenges to scale down to 10 nm node and beyond, scalable memory devices are highly sought after. The emergence of Resistive Random Access Memory (ReRAM) as a highly promising research area for next-generation non-volatile memory has garnered significant attention due to its exceptional memory performance, including high density, low power consumption, and scalability. However, the prevailing issue of sneak paths in ReRAM arrays leads to current leakage and data errors. To address this issue, the incorporation of a selector device is crucial for controlling the current flow in individual memory cells. NbOx-based Insulator-Metal Transition (IMT) devices have shown advantages as selector devices, offering fast-switching speed, high scalability, and excellent thermal stability. Additionally, their inherent Negative Differential Resistance (NDR) characteristic enables them to function as oscillatory neurons in Oscillatory Neural Networks (ONNs), mimicking biological neural networks and providing robustness and efficient information processing. This thesis focuses on studying the dynamics and characteristics of NbOx-based IMT devices for both relaxation oscillator and selector applications, and exploring their potential and performance reliability under different conditions of temperature and mechanical strain. The frequency tunability of NbOx-based oscillatory devices was investigated through various tuning methods, achieving a wide tunable range from 2 MHz to 33 MHz. The performance enhancements achieved through bulk and interfacial treatment, coupled with high endurance and operation at high oscillation frequencies, make these devices promising candidates for ONN applications, enabling enhanced information processing and efficient computing paradigms. Further investigating into the tunability of NbOx-based relaxation oscillators, the influence of oxygen stoichiometry reveals significant improvements in device performance. The findings provide insight into the factors affecting NbOx-based oscillator performance and offer opportunities for further optimization, enhancing their suitability for advanced computing architectures. The functionality of NbOx-based selector devices on flexible substrates was demonstrated, highlighting their mechanical endurance and recovery capabilities. The findings suggest the suitability of NbOx devices for flexible and wearable electronics, where mechanical flexibility and robustness are essential. Overall, this research advances the understanding and optimization of NbOx-based IMT devices, positioning them as highly promising components for next-generation memory systems and novel computing paradigms. Their demonstrated potential in terms of frequency tunability, stoichiometry optimization, and mechanical flexibility opens up avenues for further research and development. The integration of NbOx-based IMT devices into practical systems holds great promise for the future of computing and information processing.