Leakage mechanisms in BiFeO3 thin films Gary W. Pabst, Lane W. Martin, Ying-Hao Chu, and R. Ramesh Citation: Appl. Phys. Lett. 90, 072902 (2007); doi: 10.1063/1.2535663 View online: https://www.doczj.com/doc/bd15133581.html,/10.1063/1.2535663 View Table of Contents: https://www.doczj.com/doc/bd15133581.html,/resource/1/APPLAB/v90/i7 Published by the American Institute of Physics. Related Articles Large photoinduced conductivity reduction in thin films of metallic ferromagnetic manganites Appl. Phys. Lett. 99, 222507 (2011) Temperature-dependent leakage current behavior of epitaxial Bi0.5Na0.5TiO3-based thin films made by pulsed laser deposition J. Appl. Phys. 110, 103710 (2011) Probing the metal-insulator transition of NdNiO3 by electrostatic doping Appl. Phys. Lett. 99, 192107 (2011) Evidence of interface conversion and electrical characteristics improvement of ultra-thin HfTiO films upon rapid thermal annealing Appl. Phys. Lett. 99, 182904 (2011) Examination of insulator regime conduction mechanisms in epitaxial and polycrystalline SmNiO3 thin films J. Appl. Phys. 110, 094102 (2011) Additional information on Appl. Phys. Lett. Journal Homepage: https://www.doczj.com/doc/bd15133581.html,/ Journal Information: https://www.doczj.com/doc/bd15133581.html,/about/about_the_journal Top downloads: https://www.doczj.com/doc/bd15133581.html,/features/most_downloaded Information for Authors: https://www.doczj.com/doc/bd15133581.html,/authors
第45卷第4期2017年4月 硅酸盐学报Vol. 45，No. 4 April，2017 JOURNAL OF THE CHINESE CERAMIC SOCIETY https://www.doczj.com/doc/bd15133581.html, DOI：10.14062/j.issn.0454-5648.2017.04.01 铁酸铋薄膜的阻变效应和导电机制 朱慧1，张迎俏1，汪鹏飞1，白子龙2，孟晓1，陈月圆1，祁琼3 (1. 北京工业大学电子信息与控制工程学院，北京 100124； 2. 复旦大学微电子学院，上海 200433； 3. 中国科学院半导体研究所光电子器件国家工程研究中心，北京 100083) 摘要：针对脉冲激光沉积法制备的铁酸铋薄膜展开研究，利用电流–电压(I–V)特性曲线表征样品的阻变现象，对样品施加不同极性、大小的电压，其I–V曲线呈现出不同高低阻值的变化。通过对I–V曲线拟合，发现样品的导电机制符合空间电荷限制电流。结合正向电压下从高阻到低阻的转变，负向电压下从低阻到高阻的转变规律，验证样品的阻变效应符合陷阱能级的填充和脱陷，即陷阱能级的填充程度不同导致电极与铁酸铋界面势垒高度不同从而导致薄膜阻值的变化。 关键词：阻变效应；导电机制；陷阱填充与脱陷；空间电荷限制电流 中图分类号：TB34 文献标志码：A 文章编号：0454–5648(2017)04–0467–05 网络出版时间：2017–02–24 18:10:49 网络出版地址：https://www.doczj.com/doc/bd15133581.html,/kcms/detail/11.2310.TQ.20170224.1810.001.html Resistive Switching Effect and Conduction Mechanism of BiFeO3 Thin Films ZHU Hui1, ZHANG Yingqiao1, WANG Pengfei1, BAI Zilong2, MENG Xiao1, CHEN Yueyuan1, QI Qiong3 (1. The College of Electronic Information and Control Engineering, Beijing University of Technology, Beijing 100124; 2. The College of Microelectronics, Fudan University, Shanghai 200433; 3. National Engineering Research Center for Optoelectronics Devices, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083) Abstract: The resistive switching behavior of BiFeO3 thin film prepared via pulsed laser deposition was investigated. The current–voltage (I–V) curves were measured at different voltages. The resistance changes from high value to low value at a positive voltage, and the resistance changes from low value to high value at a negative voltage. The s pace charge limited conduction mechanism was analyzed through the fitting of the I–V curves. The resistive effect is attributed to the electric filed induced carrier trapping and detrapping, which results in the variation of the Schottky barrier height at the interface between the film and the electrode. Keywords: resistive effect; conduction mechanism; trapping and detrapping; s pace charge limited conduction 作为下一代最具潜力的非挥发性存储器之一的阻变存储器，因其低功耗、高存储密度、快存储速度、不易被干扰、结构简单等优势而受到广泛关注。目前，已在多种氧化物构成金属–氧化物–金属电容结构中发现阻变现象，如钙钛矿结构氧化物SrZrO3、SrTiO3和BiFeO3等[1–3]。铁酸铋(BiFeO3，BFO)是目前发现的唯一在室温以上同时表现出铁电性和铁磁性的材料，Curie温度(约1 103 K)和Neel温度(约643 K)高[4]，具有良好的电学和阻变特性，成为可应用于非挥发性铁电阻变存储器的材料之一。利用BFO制作的存储器，可通过施加不同的脉冲电压调节高低阻态之间的转换，以达到存储的目的，并且能够显著增加存储密度而不增加存储器尺寸。 BFO的禁带宽度约为2.67 eV，亲和能χ约为3.3 eV，其功函数约为4.7 eV[5]。当选择功函数大于BFO的金属电极时，电子会从BFO向金属电极迁移，直到金属和BFO拥有相同的Fermi能级，失去电子的正电荷在BFO表面形成一个耗尽区，从而在接 收稿日期：2016–06–27。修订日期：2016–12–21。 基金项目：国家自然科学基金(61201046，61306057)；北京市自然科学基金(4162013，2132023)；北京市博士后工作经费资助项目 (2015ZZ–33)；北京市教委科技计划一般项目 (KM201610005005)；教育部留学回国人员科研启动基金。第一作者：朱慧(1980–)，女，博士，副教授。Received date: 2016–06–27. Revised date: 2016–12–12. First author: ZHU Hui (1980–), female, Ph.D., Associate Professor. E–mail: zhuhui@https://www.doczj.com/doc/bd15133581.html,
Appl Phys A(2014)114:853–859 DOI10.1007/s00339-013-7712-5 Structural,optical,and multiferroic properties of single phased BiFeO3 M.Muneeswaran·P.Jegatheesan·M.Gopiraman· Ick-Soo Kim·N.V.Giridharan Received:26December2012/Accepted:13April2013/Published online:27April2013 ?Springer-Verlag Berlin Heidelberg2013 Abstract A soft chemical coprecipitation method has been proposed for synthesis of nano-sized multiferroic BiFeO3 (BFO)powders.The X-ray diffraction pattern con?rms the perovskite structure of BFO and Rietveld re?nement re-veals the existence of rhombohedral R3c symmetry.Crys-tallite size and strain value are studied from Williamson–Hall(W–H)analysis.The transmission electron microscope (TEM)image shows that the particle size of BFO powders lies between50–100nm.4A1and7E Raman modes have been observed in the range100–650cm?1and a prominent band centered around1150–1450cm?1have also been ob-served corresponding to the two-phonon scattering.Differ-ential Thermal Analysis(DTA)shows the existence of two prominent peaks at330?C and837?C corresponding to the magnetic and ferroelectric ordering,respectively.From the temperature dependent dielectric studies,an anomaly in the dielectric constant is observed at the vicinity of Neel tem-perature(T N)indicating a magnetic ordering.Also,BFO shows antiferromagnetic behavior measured from the mag-netic studies. 1Introduction Recently,the interest in multiferroics is stimulated by fun-damental physics leading to multiferroism arising from cou-M.Muneeswaran·P.Jegatheesan·N.V.Giridharan( ) Department of Physics,National Institute of Technology, Tiruchirappalli620015,India e-mail:giri@https://www.doczj.com/doc/bd15133581.html, Fax:+91-431-2500133 M.Gopiraman·I.-S.Kim Nano Fusion Technology Research Group,Faculty of Textile Science and Technology,Shinshu University,Ueda, Nagano386-0015,Japan pling between magnetic and ferroelectric orderings,and have been extensively studied for their possible technical applications,including spintronics,microelectronics,mag- netic memory,and sensors[1].The term“multiferroic” means coexistence of ferroelectric and magnetic ordering in one single phase or multiphase materials.However,these two ordering parameters are mutually exclusive in principle because ferroelectricity requires empty d shells,while mag- netism requires partially?lled d shells[2].Several compos- ite materials,consisting of separate ferroelectric and mag- netic phases,have been reported to show magnetoelectric coupling at room temperature[3].However,the availabil- ity of room-temperature single phase multiferroics is very limited[4].Among the few room temperature single-phase multiferroics reported so far[5],BiFeO3(BFO)is an im- portant multiferroics,which has rhombohedrally distorted perovskite crystal structure with a space group of R3c at room temperature[6].It exhibits ferroelectric ordering be- low T C～1083–1103K,and antiferromagnetic ordering be-low T N～625–643K[7].BFO shows G-type antiferromag-netic structural behavior having modulated spiral spin struc- ture with long periodicity of62nm in the unit cell[8].In- terests shown by the researchers to work on these materi- als in a nanoregime is due to their size dependent proper- ties compared to the bulk.Nanosized BFO powders have been reported to exhibit weak ferromagnetism at room tem- perature,which is different from the magnetic property of bulk samples[9].One important challenge in the success- ful synthesis of pure BFO is avoiding the secondary phases such as Bi2Fe4O9and Bi25FeO39[10].Several techniques have been developed to prepare pure BFO powders.The solid state reaction route generally involves a higher pro- cessing and requires HNO3as a leaching agent to elimi- nate the secondary phases leading to the coarse nature of the powders.Nanosized BFO ceramics have been prepared
铁磁性材料 铁磁性物质属强磁性材料， 它在电工设备和科学研究中的 应用非常广泛，按它们的化学成 分和性能的不同，可以分为金属 磁性材料和非金属磁性材料（铁 氧体）两大族。 1 金属磁性材料 金属磁性材料是指由金属合 金或化合物制成的磁性材料，绝 大部分是以铁、镍或钴为基础，再加入其他元素经过高温熔炼、机械加工热处理而制成，这种磁性材料在高温、低频、大功率等条件下，有广泛的应用，但在高频范围，它的应用则受到限制。金属磁性材料还可分为硬磁、软磁和压磁材料等，实验表明，不同铁磁性物质的磁滞回线形状有很大差异，图示给出了三种不同铁磁材料的磁滞回线，其中，软磁性材料的面积最小；硬磁材料的矫顽力较大，剩磁也较大；而铁氧体材料的磁滞回线则近似于矩形，故亦称矩磁材料。 软磁材料的特点是相对磁导率r 和饱和磁感强度max B 一般都比较大，但矫顽力c H 比硬磁质小得多 ，磁滞回线所包围的面积很小，磁滞特性不显著如图(a)，软磁材料在磁场中很容易被磁化，而由于它的矫顽力很小，所以也容易去磁，因此，软磁材料是很适宜于制造电磁铁、变压器、交流电动机、交流发电机等电器中的铁心的另一个原因。 硬磁材料又称永磁材料，它的特点是剩磁r B 和矫顽力c H 都比较大，磁滞回线所包围的面积也就大， 磁滞特性非常显著如图(b)，所以把硬磁材料放在外磁场中充磁后，仍能保留较强的磁性，并且这种剩余磁性不易被消除，因此硬磁材料适宜于制造永磁体。在各种电表及其他一些电器设备中，常用永磁铁来获得稳定的磁场。1998年6月3日，由美国“发现者号”航天飞机携带的、美籍华裔物理学家丁肇中教授组织领导的阿尔法磁谱仪上所用的永磁体，就是由中国科学院电工研究所等单位研制的稀土材料钕铁硼永磁体，其磁感强度高达0. 14T ，该永磁体的直径为1. 2m ，高0. 8m ，而阿尔法磁谱仪是用来探测宇宙中反物质和暗物质的，这是人类第一次将大型永磁铁送入宇宙空间，对宇宙中的带电粒子进行直接观测，它极有可能给人类开拓一个全新的科学领域而带来一次新的科学突破。 压磁材料具有强的磁致伸缩性能，所谓磁致伸缩是指铁磁性物体的形状和体积在磁场变化时也会发生变化，特别是改变物体在磁场方向上的长度。当交变磁场作用在铁磁性物体上时，它随着磁场的增强，可以伸长，或者缩短，如钴钢是伸长，而镍则缩短，不过长度的变化是十分微小的，约为其原长的1/100000，磁致伸缩在技术上有重要的应用，如作为机电换能器用于钻孔、清洗，也可作为声电换能器用于探测海洋深度、鱼群等。 2 非金属磁性材料——铁氧体 铁氧体，又叫铁淦氧，是一族化合物的总称，它由三氧化二铁（Fe 2O 3）和其他二价的金属氧化物（如
【名】 (形声。从金,臷(zhì)声。本义:化学元素。符号Fe。一种很重的可锻、有延展性和有磁性的、主要是两价和三价的金属元素,纯铁为银白色,但在潮湿空气中容易生锈) 同本义〖iron〗 铁,黑金也。——《说文》 铁锁长三丈。——《墨子·备穴》 邯郸郭纵以冶铁成业。——《史记·货殖列传》 又如:铁冶(冶铁工场);铁山(产铁的矿山);铁石(铁与石;铁矿石);铁锡(铁和锡);铁砂(含铁的矿砂);铁炭(铁和炭);铁皮(铁的外层);铁精(纯铁) [编辑本段] 【铁制的器物（ironware）】 柄铁折叠环复——明·魏禧《大铁椎传》 又如:铁花(金属器物的光泽);铁戒尺(佛教徒戴在头上的环形物);铁尺(铁戒尺;用 来体罚的铁板子);铁锚(用来作为停船时稳定船身的铁制大钩子);铁鼓(铁制的战鼓);铁绠(铁索,铁绳);铁牌(铁制的牌子);铁钵(铁制的钵。僧人化缘求食的用具);铁钩(铁制的钩子);铁箍(铁制的圆环,用以箍物。如木桶之类可用铁箍箍住,使不松开) 指兵器〖arms;weapon〗 如:铁蒺藜骨朵(古代的一种兵器,以铁或硬木制成,为一长棒,顶端为附有铁刺的长圆形头);铁蒺藜(军用的铁制三角物,尖刺如蒺藜籽。常布设于地上或浅水中,阻碍人马、车辆行动);铁兵(铁制兵器);铁杖(铁制的棍棒);铁衣(用铁片制成的战衣) 赤黑色的马〖blackandredhorse〗 乘玄路,驾铁骊。——《礼记·月令》 古丘名〖Tiehill〗 春秋时卫地。在今河南濮阳北 姓 如:铁力(复姓);铁弗(复姓);铁伐(复姓) 【形】 黑色〖black〗 如:铁色(像铁的颜色。即铁灰色);铁骢(毛色青黑的马);铁骊(毛色青黑如铁的马);铁连钱(指马身上黑色的钱形斑点);铁藓(黑色苔藓) 比喻坚固〖hardorstrongasiron〗 如:铁郭(形容外城坚固如铁);铁壁(比喻城壁或荼诘募峁?;铁纱帽(比喻稳固的官职);铁脚板(形容善于长途行走的脚);铁屋(比喻监狱) 比喻坚强不屈;强硬〖firm;solid〗 如:铁石(比喻意志坚强刚毅);铁誓(坚定不二、至死不变的誓言);铁砚未穿(除非铁砚磨穿,所定志向决不动摇。比喻意志坚定,未达既定目的,决不改变);铁心肠(形容意志坚定,不为感情所动) 驳不倒的〖irrefutable〗