HfO_x缓冲层对γ-Fe_2O_3纳米微粒膜电阻开关特性的影响

Effect of HfO_x buffer layer on the resistive switching characteristics of γ-Fe_2O_3 nanoparticle films

本文利用射频磁控溅射和滴涂法在Pt/Ti/SiO2/Si衬底上制备了HfOx/γ-Fe2O3/HfOx三明治结构,研究了HfOx缓冲层对γ-Fe2O3纳米微粒薄膜电阻开关特性的影响.微结构观测分析结果显示:γ-Fe2O3纳米微粒平均粒径约为34.3 nm,HfOx缓冲层为氧配比不足的单斜相多晶薄膜.电学性能测试表明:插入HfOx缓冲层后,γ-Fe2O3纳米微粒薄膜的电阻开关特性明显改善:在-0.8 V读取电压下,高/低电阻态阻值平均比值约为18.7,该比值可稳定维持>100个循环周期.指数定律拟合实验曲线结果表明:高阻态漏电流以缺陷主导的空间电荷限制隧穿电流为主;而低阻态则以欧姆接触电导为主.Ag上电极与HfOx缓冲层界面处氧离子的定向漂移使得薄膜中氧空位缺陷形成的导电细丝通道周期性地导通与截断,从而使得薄膜呈现电阻开关效应.

100 nm HfOx/γ-Fe2O3/50 nm HfOx sandwich structures have been fabricated on Pt/Ti/SiO2/Si（100） substrates by radio frequency magnetron sputtering combined with spin-coating methods. Scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectra investigations reveal that the oxygen-deficient HfOx buffer layers exhibit a monoclinic polycrystalline structure, and the self-organized γ-Fe2O3 nano-particles have an average diameter of 34. 3 nm. After inserting the upper and bottom HfOx buffer layers, γ-Fe2O3 nanoparticle film exhibits a more notable and stable bipolar resistive switching memory characteristic： the ratio of high and low resistance at the reading voltage of -0.8 V is about 18.7. This on/off ratio can be well maintained after 100 switching cycles, suggesting a good durability of memory characteristics. The logarithmic plots and power-law fittings for current-voltage curves demonstrates that a trap-controlled space-charge limited current conduction process is responsible for the current transport in the high resistance state, while a ohmic conduction process is dominated in the low resistance state. The drift of oxygen ions at the interface between Ag top electrodes and the HfOx buffer layer results in the formation and annihilation of a conductive filament, which is responsible for the resistive switching.