赝弹性银硫系化合物阻变行为的透射电镜研究

赝弹性银硫系化合物阻变行为的透射电镜研究

熊雨薇，李京仓，谭治远，朱明芸，尹奎波^*，商尚炀，魏  琦，夏奕东，孙立涛^*

（1.东南大学-FEI 纳皮米中心，MEMS 教育部重点实验室，东南大学电子科学与工程学院，江苏南京210096；2.固体微结构国家实验室，南京大学材料科学与工程学院，江苏南京210093）

摘  要 银硫系化合物由于尺寸可缩减性好、擦写速度快、具有多值存储能力等优点，在阻变存储器介质材料研究中受到广泛关注。但随着介质材料尺寸的不断缩小，材料表/界面结构对器件的性能产生的影响尚不明确。因此从微观尺度上揭示阻变介质材料表/界面对性能影响的相关机理至关重要。本文利用脉冲激光沉积制备了Ag₁₀Ge₁₅Te₇₅薄膜，并在透射电子显微镜中构建了以其为介质的阻变存储器，研究了其阻变过程中微观形貌与物相的演化。实验发现，尺寸在20 nm以下的Ag₁₀Ge₁₅Te₇₅薄膜在被电压脉冲熔断后，能够用“冷焊”的方式重新连接并仍保持阻变特性。当给其施加正向电压时，薄膜中生成Ag₂Te多晶颗粒。当挤压拉伸薄膜时，Ag₂Te多晶颗粒不会消失。当施加反向电压时，Ag₂Te多晶颗粒消失。分析认为，Ag₁₀Ge₁₅Te₇₅薄膜的形变属于Coble赝弹性，Ag₂Te多晶的生成与电场诱导沉积有关。实验的结果对于构建新型柔性阻变存储器结构具有一定的指导意义。

关键词 Ag₁₀Ge₁₅Te₇₅；透射电子显微镜；阻变存储器；赝弹性行为

中图分类号：TB303；TN303；TN304；TN604；TG115.21⁺5.3 

文献标识码：Adoi:10.3969/j.issn.1000-6281.2021.06.001

Investigation of the resistive switching behavior of pseudoelastic silver chalcogenides via TEM

XIONG Yu-wei¹，LI Jing-cang¹，TAN Zhi-yuan¹，ZHU Ming-yun¹，YIN Kui-bo^1*，SHANG Shang-yang¹，WEI Qi¹，XIA Yi-dong¹，SUN Li-tao^1*

(1.SEU-FEI Nano-Pico Center, Key Laboratory of MEMS of Ministry of Education, Department of Electronic Science and Engineering, Southeast University, Nanjing Jiangsu 210096；National Laboratory of Solid State Microstructures, Department of Materials Science and Engineering, Nanjing University, Nanjing Jiangsu 210093, China)

Abstract   Silver chalcogenide has been one of the most attractive dielectric materials in resistive random-access memory (RRAM) due to its excellent miniaturization potential, fast operation speed and multilevel data storage capacity. However, the influence of material surface/interface structure on device performance is ambiguous as the size of dielectric material decreases. Therefore, it is significant to reveal the corresponding mechanism of dielectric materials at atomic scale. In this paper, Ag₁₀Ge₁₅Te₇₅ films were prepared by pulsed laser deposition, and a RRAM device based on the Ag₁₀Ge₁₅Te₇₅ films was constructed in the transmission electron microscope (TEM). The evolution of morphology and phase during the resistive switching process was studied. It was found that the Ag₁₀Ge₁₅Te₇₅ thin films with the sizebelow 20 nm could be reconnected by cold welding after being fused by voltage pulse and still retain resistive switching characteristics. When the forward voltage is applied, Ag₂Te particles are formed in the film. Ag₂Te particles will not disappear until the reverse voltage is applied, even though the film is compressed or stretched. It can be concluded that the deformation of Ag₁₀Ge₁₅Te₇₅ film belongs to Coble pseudoelasticity, and the formation of Ag₂Te is related to electrical field induced precipitation reaction. This work provides deep insights into mechanistic understanding of resistive switching in Ag₁₀Ge₁₅Te₇₅ and a valuable strategy for producing flexible RRAM.

Keywords   Ag₁₀Ge₁₅Te₇₅; transmission electron microscope; RRAM; pseudoelastic behavior

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