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电极材料及偏压极性对氧化物介质击穿行为的影响及机制
引用本文:王彦彬,刘倩,王勇,代波,魏贤华.电极材料及偏压极性对氧化物介质击穿行为的影响及机制[J].物理学报,2021(8):341-347.
作者姓名:王彦彬  刘倩  王勇  代波  魏贤华
作者单位:西南科技大学
基金项目:国家自然科学基金(批准号:51772252);四川省科技计划(批准号:2020JDRC0062);西南科技大学环境友好能源材料国家重点实验室项目(批准号:18FKSY0202,19FKSY09)资助的课题。
摘    要:忆阻器和能量存储电容器具有相同的三明治结构,然而两个器件需要的操作电压有明显差异,因此在同一个器件中,研究操作电压的影响因素并对操作电压进行调控,实现器件在不同领域的应用是十分必要的一个工作.本文利用反应磁控溅射技术在ITO导电玻璃、Pt/Si基底上生长了多晶ZrO_2和非晶TaO_x薄膜,选用不同金属材料Au, Ag和Al用作上电极构建了多种金属/氧化物介质/金属三明治结构的电容器,研究了器件在不同偏压极性下的击穿强度.结果发现:底电极是ITO的ZrO_2基电容器在负偏压下的击穿电场比Pt电极器件稍大.不管底电极是ITO还是Pt, Ag作为上电极时器件的击穿强度均存在明显的偏压极性依赖性,正偏压下的击穿电场减小了一个数量级;相反,在Al作为上电极的Al/TaO_x/Pt器件中,正向偏压比负向偏压下的击穿电场增加了近2倍.上述器件的不同击穿行为分别可以由氧化物电极和介质界面层间氧的迁移和重排、电化学活性金属电极的溶解迁移和还原以及化学活性金属电极与氧化物界面的氧化还原反应来解释.该实验结果对有不同操作电压要求的器件,如忆阻器和介质储能电容器等在器件设计和操作方面具有指导意义.

关 键 词:氧化物薄膜  电极材料  偏压极性  击穿机理  忆阻器  电容器

Effects of electrode materials and bias polarities on breakdown behaviors of oxide dielectrics and their mechanisms
Wang Yan-Bin,Liu Qian,Wang Yong,Dai Bo,Wei Xian-Hua.Effects of electrode materials and bias polarities on breakdown behaviors of oxide dielectrics and their mechanisms[J].Acta Physica Sinica,2021(8):341-347.
Authors:Wang Yan-Bin  Liu Qian  Wang Yong  Dai Bo  Wei Xian-Hua
Affiliation:(State Key Laboratory of Environment-friendly Energy Materials,Southwest University of Science and Technology,Mianyang 621010,China)
Abstract:The memristors and the energy storage capacitors have the same sandwich structure,but the operating voltages required by the two devices are significantly different.Therefore,in the same device,it is necessary to study the influencing factors of operating voltage and adjust the operating voltage of the devices to realize the applications of the device in diverse fields.The polycrystalline ZrO2 and amorphous TaOx thin films are deposited on ITO conductive glass and Pt/Si substrates by reactive magnetron sputtering technology.Au,Ag and Al metal materials are selected as the top electrodes to construct a variety of metal/insulator/metal sandwich capacitors.The breakdown strengths of these devices under different bias polarities are studied.The results demonstrate that the breakdown strength is slightly larger for the ZrO2 based capacitor with ITO as the bottom electrode than for the Pt electrode device under negative bias.The breakdown electric field of the device with Ag as the top electrode shows obvious dependence on bias polarity,no matter whether the bottom electrode is ITO or Pt.The breakdown strength is reduced by more than an order of magnitude under a positive bias(2.13 MV/cm)compared with under a negative bias(0.17 MV/cm)of Ag/ZrO2/ITO device.The breakdown strength of the Al/TaOx/Pt device is enhanced under the forward bias(3.6 MV/cm),contrary to the Ag electrode device,which is nearly twice higher than the breakdown electric field under the negative bias(1.81 MV/cm).The different breakdown behaviors of the above devices can be explained by the migration and rearrangement of oxygen between the oxide electrode and the dielectric interface layer;the dissolution,migration and reduction of the electrochemically active metal electrode;and the redox reaction between the chemically active metal electrode and the oxide dielectric interface.The ZrO2 based capacitor with ITO electrode undergoes a redox reaction of Sn4+in the ITO under negative bias,forming an insulating layer at the interface between the dielectric layer and the ITO electrode,which contributes a larger breakdown electric field.In addition,the electrochemical metallization process happens to the Ag electrode device under positive bias,and the breakdown electric field is smaller than negative bias due to the large diffusion coefficient of Ag ions in the film,while breakdown is dominated by the defect characteristics of the dielectric film under negative bias.The Al/TaOx/Pt devices can form AlOx oxide layer under positive bias,spontaneously,which can inhibit the leakage current,and also act as a series resistance to disperse part of the voltage and enhance the breakdown voltage of the device.The experimental results have guided significance in designing and operating the devices with different operating voltage requirements,such as memristors and dielectric energy storage capacitors.
Keywords:oxide films  electrode materials  bias polarity  breakdown mechanism  memristors  capacitors
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