Lee Hye Jin, Kim Jeong-Hyeon, Lee Seung Hun, Lee Sung-Nam
Department of IT & Semiconductor Convergence Engineering, Tech University of Korea, Siheung 15073, Republic of Korea.
Department of Nano & Semiconductor Engineering, Tech University of Korea, Siheung 15073, Republic of Korea.
Nanomaterials (Basel). 2024 Dec 8;14(23):1972. doi: 10.3390/nano14231972.
This study presents the fabrication and characterization of a dual-functional Pt/GaO/Pt optoelectronic synaptic device, capable of operating as both a memristor and a memcapacitor. We detail the optimized radio frequency (RF) sputtering parameters, including a base pressure of 8.7 × 10 Torr, RF power of 100 W, working pressure of 3 mTorr, and the use of high-purity GaO and Pt targets. These precisely controlled conditions facilitated the formation of an amorphous GaO thin film, as confirmed by XRD and AFM analyses, which demonstrated notable optical and electrical properties, including light absorption properties in the visible spectrum. The device demonstrated distinct resistive and capacitive switching behaviors, with memory characteristics highly dependent on the wavelength of the applied light. Ultraviolet (365 nm) exposure facilitated long-term memory retention, while visible light (660 nm) supported short-term memory behavior. Paired-pulse facilitation (PPF) measurements revealed that capacitance showed slower decay rates than EPSC, suggesting a more stable memory performance due to the dynamics of carrier trapping and detrapping at the insulator interface. Learning simulations further highlighted the efficiency of these devices, with improved memory retention upon repeated exposure to UV light pulses. Visual encoding simulations on a 3 × 3 pixel array also demonstrated effective multi-level memory storage using varying light intensities. These findings suggest that GaO-based memristor and memcapacitor devices have significant potential for neuromorphic applications, offering tunable memory performance across various wavelengths from ultraviolet to red.
本研究展示了一种双功能Pt/GaO/Pt光电突触器件的制备与表征，该器件能够同时作为忆阻器和忆容器工作。我们详细介绍了优化后的射频（RF）溅射参数，包括8.7×10托的基压、100瓦的射频功率、3毫托的工作压力，以及使用高纯度的GaO和Pt靶材。这些精确控制的条件有助于形成非晶态GaO薄膜，XRD和AFM分析证实了这一点，分析表明该薄膜具有显著的光学和电学特性，包括在可见光谱中的光吸收特性。该器件表现出明显的电阻式和电容式开关行为，其记忆特性高度依赖于所施加光的波长。紫外线（365纳米）照射有助于长期记忆保持，而可见光（660纳米）则支持短期记忆行为。双脉冲易化（PPF）测量表明，电容的衰减速率比兴奋性突触后电流（EPSC）慢,这表明由于绝缘体界面处载流子俘获和脱俘获的动力学，记忆性能更稳定。学习模拟进一步突出了这些器件的效率，在重复暴露于紫外光脉冲时，记忆保持得到改善。在3×3像素阵列上的视觉编码模拟也证明了使用不同光强度进行有效的多级记忆存储。这些发现表明，基于GaO的忆阻器和忆容器器件在神经形态应用方面具有巨大潜力，能够在从紫外到红色的各种波长范围内提供可调谐的记忆性能。
