NiO_x多晶薄膜的变温电阻开关特性与隧穿机制  

Temperature-dependence of resistive switching behaviors and tunneling mechanism of polycrystalline NiO_x films

作　　者：王瑞雪[1] 张婷[1] 李鲁涛[1] 魏明龙[1] 孟祥申[1] 邱晓燕[1] WANG RuiXue ZHANG Ting LI LuTao WEI MingLong MENG XiangShen QIU XiaoYan(School of Physical Science and Technology, Southwest University, Chongqing 400715, China)

机构地区：[1]西南大学物理科学与技术学院,重庆400715

出　　处：《科学通报》2017年第11期1163-1171,共9页Chinese Science Bulletin

基　　金：国家自然科学基金(11274257);重庆市自然科学基金(cstc2014jcyj A40029);中央高校基本科研业务费专项(XDJK2014B043;XDJK2016E123)资助

摘　　要：利用射频磁控溅射方法沉积制备了Ag/NiO_x/Pt存储单元,研究了其微结构、电阻开关特性随测试温度的变化.微结构观测分析发现,沉积制备薄膜为富氧的NiO_x多晶薄膜.Ag/NiO_x/Pt存储单元的电流-电压测试曲线呈现阈值型电阻开关特性:分别在2.1~2.4 V的正偏压范围和-2^-2.2 V的负偏压范围内观测到了高低电阻态之间的稳定可逆跳变.随着测试温度的升高,负偏压范围的电阻开关现象在140℃基本消失,而正偏压范围内的电阻开关现象可维持到270℃.运用指数定律拟合室温电流-电压曲线结果表明,薄膜隧穿电流属于缺陷主导的空间限制电流;运用Arrhenius作图法拟合的电流-温度曲线满足线性关系,表明薄膜隧穿电流随测试温度的变化符合肖特基热激发隧穿机制.在周期性电场作用下,从银电极扩散进入薄膜内的Ag离子的氧化还原反应导致存储单元呈现阈值型电阻开关特性.Resistive switching random access memory（Re RAM） based on resistive switching of oxide films is one of potential candidates for next generation of nonvolatile memory due to its simple structure, high writing/read speed and low power consumption. NiO_x thin film is one of oxide materials early observed resistive switching behaviors and the most promising materials for the application of commercial oxide resistance memory. However, NiO_x thin films present diverse resistive switching behaviors which are heavily dependent on fabrication technologies, methods and conditions. From 1960 s, researchers have focused on optimizations of device structure and improvements on switching performance parameters of NiO_x-based ReR AMs at room temperature. On the contrary, there is few discussions on temperature-dependence of resistive switching behaviors of NiO_x thin films. In this paper, temperature-dependence of resistive switching behaviors and tunneling mechanism of polycrystalline NiO_x films have been discussed. 120 nm-thick NiO_x films have been deposited at 280°C on Pt-covered Si（100） substrates in 0.5 Pa Ar＋O2 mixed ambient by using radio frequency magnetron sputtering with a working power of 60 W. Scanning electron microscope images reveal the as-deposited film exhibits a dense and smooth surface morphology. X-ray diffraction patterns and X-ray photoelectron spectra reveal it is polycrystalline and oxygen-riched NiO_x. After being covered by a 150 nm-thick Pt top electrode with a diameter of 0.2 mm, a Ag/NiO_x/Pt memory cell is obtained. Its current-voltage（I-V） curves exhibit threshold-type resistive switching characteristics： under the positive bias ranging from 2.1 to 2.4 V and the negative bias from-2 to-2.2 V, one can see stable and reversible switching between the high and low resistance state. With the increase of measurement temperature, the I-V loop within the negative bias range vanishes at 140°C, while it maintains up to 270°C within the positive bias range. Power-law fitting lines for th

关 键 词：NiOx多晶薄膜 电阻开关特性 温度依赖性 隧穿机制 

分 类 号：O484[理学—固体物理]