异质结薄膜的铁电、磁性能及漏电流研究

采用溶胶凝胶方法在Si（100）衬底上生长了SrBi2Ta2O9/LaNiO3 (SBT/LNO)异质结薄膜,其中SrBi2Ta2O9薄膜呈高度（115）取向.测量了不同退火温度下异质结的电滞回线和漏电流密度,结果表明,700 ℃下退火的薄膜剩余极化值最高,漏电流最低,且表现出弱的室温铁磁行为.漏电流机理分析表明薄膜界面为欧姆接触.     

MOD法制备SrBi2Ta2O9铁电薄膜及其性能研究

在Pt/TiO2/SiO2/Si衬底上,用金属有机物分解法(MOD)制备了SrBi2Ta2O9(SBT)铁电薄膜.研究了SBT薄膜的晶体结构,表面形貌以及它的电学性能,结果表明SrBi2Ta2O9铁电薄膜具有良好的抗疲劳特性,在经过109次极化反转后其剩余极化强度Pr变化不大,约为3%,并且漏电流较低,在测量电压为1V时,漏电流密度为5.73×10-8A/cm2.     

不同退火气氛下Bi2NiMnO6薄膜的铁电性能和漏电流研究

采用化学溶液法以LaNiO₃为底电极在Si(100)衬底上生长了Bi₂NiMnO₆薄膜,分别在N₂和O₂下对薄膜进行退火,退火温度均为600 ℃,研究不同退火气氛对薄膜结构与电性能的影响.用XRD测量分析了Bi₂NiMnO₆薄膜的结构,用铁电性能测量仪表征了样品的铁电性能和漏电流特性.结果表明,在N₂或O₂气氛下,Bi₂NiMnO₆薄膜均能成相,所有样品在室温下均表现出铁电性能,同时,这些样品都呈现出相当低的漏电流密度.此外,还讨论了Bi₂NiMnO₆薄膜的导电机制.     

Ar气退火温度对4H-SiC热氧化层致密性影响研究

在Ar气气氛下对热氧化n型4H-SiC生长的SiO2薄膜进行了1100 ℃以下不同温度的退火, 采用反射式椭圆偏振光谱、红外透射光谱研究了退火温度对SiO2薄膜致密性的影响. 椭偏测试的结果表明, 600 ℃退火后样品具有最大的折射率1.47和最小的厚度84.63 nm. 红外研究的结果显示, 600 ℃退火后LO峰强度最强, 认为是对应Si-O结构单元浓度最高. Al/SiO2/SiCMOS结构SiO2的漏电特性研究表明, 600 ℃退火后的SiO2薄膜漏电流相比于其他温度退火的氧化层漏电流小了两个数量级. 在外加反向偏压5V时, 漏电流密度仅仅只有5×10-8 A/cm2.600 ℃退火能显著地改善热氧化层SiO2的致密性.     

氧气氛退火对磁控溅射Ta2O5薄膜结构、表面形貌及电学性能的影响

本文采用磁控溅射在Si基体上制备Ta2O5薄膜,研究了退火前、500℃氧气氛退火半小时之后、800℃氧气氛退火半小时之后的Ta2O5薄膜的结构、表面形貌及电学性能.退火前和500℃退火的薄膜均为非晶薄膜,但500℃退火之后能使非晶薄膜结构更加致密,表面更加平整,并且给薄膜进行了补氧,提高了薄膜的绝缘性能.800℃退火之后的薄膜出现了结晶颗粒,晶界引起了大的漏电流,使薄膜的绝缘性能下降.     

Ta2O5/MnO2复合湿敏薄膜制备工艺研究

采用钽片阳极氧化和硝酸锰热分解方法，制备Ta2O5/MnO2复合薄膜，研究了电解液种类、浓度（质量分数）、电压对Ta2O5/MnO2复合薄膜绝缘性能的影响。     

Ta掺杂VO2多晶薄膜的相变特性

以氧化二乙酰丙酮合钒（C10H14O5V）为前驱体,乙醇钽[Ta（OC2H5）5]为掺杂剂,用溶胶-凝胶方法在Si（100）和SiO2/Si衬底上制备了V1-xTaxO2（x=0-0.1）多晶薄膜。XRD谱图显示薄膜呈（011）面取向生长。随着Ta掺杂量的增大,d（011）基本呈线性增大表明Ta替代了V在晶格中的位置,实现了替位掺杂。每掺杂1%原子比的Ta,相变温度降低7.8℃,相变热滞减小1℃。SiO2/Si衬底上5%原子比掺杂薄膜的相变温度为29.5℃,室温（300 K）电阻-温度系数（TCR）为-8.44%/K。两种衬底上掺杂V0.9Ta0.1O2薄膜的升温和降温电阻-温度曲线基本重合。实验结果显示,Ta是降低VO2薄膜的相变温度和消除相变热滞的有效掺杂剂。     

CsLaTa2O7/Na2Ta2O6异质结构的构建及光催化性能

利用层状结构CsLaTa2O7的亚稳特性,通过水热法在其表面原位合成烧绿石型Na2Ta2O6粒子,构建出CsLaTa2O7/Na2Ta2O6异质结构光催化剂。利用XRD、SEM、TEM、UV⁃Vis光谱和荧光光谱等测试手段,对CsLaTa2O7/Na2Ta2O6样品进行表征。结果表明,CsLaTa2O7/Na2Ta2O6异质结构可以有效地抑制光生电子和空穴的复合,并且在紫外光下光照10 min就能将亚甲基蓝染料完全降解,其紫外光下光催化性能明显高于单一相。     

Ta2O5材料光学常数的拟合及其在近紫外到近红外波段应用

Ta2O5在近紫外到近红外波段作为高折射率材料有着广泛的应用,由于色散和吸收,Ta2O5在不同波段的光学常数不尽相同.此外,不同的制备条件下,Ta2O5材料的光学常数也会出现差异.如何精确得出Ta2O5材料在确定工艺条件下的光学常数成了薄膜工作者关心的话题.本文介绍了一种采用电子枪蒸发并加以离子束辅助技术制备Ta2O5薄膜的方法,对薄膜从近紫外到近红外的光学常数进行了拟合,并举例说明了Ta2O5材料在近紫外波段的应用.     

底电极对BiFeO3薄膜电性质的影响

用溶胶-凝胶方法在LaNiO3,ITO和Pt底电极上制备了BiFeO3(BFO)薄膜.薄膜的退火温度为550℃.对不同底电极上的BFO薄膜的结构、形貌、铁电性、介电性和漏电流特性进行了研究.XRD研究表明不同底电极上的BFO薄膜呈不同的取向.所有的薄膜都没有观察到不纯相.剖面扫描电镜研究表明薄膜的厚度为350nm.铁电性测试表明在128kV/cm的测试电场下LaNiO3底电极上的薄膜的剩余极化强度最大,为3.31μC/cm2.而ITO和Pt底电极上的BFO薄膜的剩余极化强度分别为2.07μC/cm2与2.76μC/cm2.此外,漏电流的研究表明在ITO底电极上的BFO薄膜的漏电流最小.     

Preparation and properties of SrBi_(2.2) Ta_2O_9 thin film

1INTRODUCTION Ferroelectricfilmshaveattractedmuchatten tionduetotheirpotentialapplicationsinelectronic devices,suchaspyroelectricinfrareddetectors,opticalswitches,actuators,dynamicrandomac cessmemories(DRAMS)[1,2],andnon volatile randomaccessmemories(NVRAMS)[3,4].Re cently,thereisinterestinthestudyofbismuthlayerstructuredferroelectricmaterialsformemory applications.Inparticular,strontiumbismuthtan tanate(SBT),oneofthebismuthlayerstructuredcompounds,isapromisingcandidateforferroelec t…     

Highfield effects of layered perovskite ferroelectric thin films

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Preparation and properties of SrBi2.2 Ta2O9 thin film

SrBi_2.2 Ta₂O₉ (SBT) thin film with thickness of 2 μm was successfully prepared by sol-gel method, using strontium acetate semihydrate [Sr(CH₃ COO)₂ · 1/2H₂O] and bismth subnitrate [BiO(NO₃)], and tantalum ethoxide [Ta(OCH₂CH₃)₅] as source materials, glacial acetic and ethylene glycol as solvents. The X-ray diffraction (XRD) and transmission electron microscope(TEM) results indicate that SBT layer-perovskite phase obtained has to be single phase, SBT thin film is formed after being annealed at 800 °C for for 1 min. The typical hysteresis loop of SBT thin film on Pt/Ti/SiO₂/Si is obtained, and the measured polarization value of the SBT thin film is 4. 2 μ/C/cm². Foundation item: Project (HIT. 2001. 67) supported by the Scientific Research Foundation of Harbin Institute of Technology; project (50172012) supported by the National Natural Science Foundation of China     

Preparation and characterization of nanocrystalline SnO2 thin film by electrodeposition technique

A novel process for preparing tin oxide thin films directly on copper foil by electrodeposition was developed. An optimal preparation technology to obtain SnO2 thin films was proposed with current density of 8 mA/cm2, the time of deposition of 120 min, the concentration of tin dichloride of 0.02 mol/L and the concentration of dissociated acid of 0.03 mol/L. The phase identification, microstructure and morphology of the thin films were investigated by thermogravimetric analysis and differential thermal analysis, X-ray diffraction, Fourier transform infrared spectra,scanning electron microscopy and transmission electron microscopy. The as-deposited thin film was composed of SnO2·xH2O was obtained by drying at room temperature. Nanocrystalline SnO2 thin film having tetragonal structure with average grain size in the range of 8 to 20 nm and porous, uniform surface was obtained by heat-treating the as-deposited film at 400 ℃ for 2 h. Electrochemical characterization shows that SnO2 film can deliver a discharge capacity of 798 mAh/g and the SnO2 film with smooth surface and annealed at 400 ℃ for 2 h has better cycle performance than that with rough surface and annealed at 150 ℃ for 10 h.     

溶胶-凝胶法制备（Nd,Bi）_4Ti_3O_（12）铁电薄膜

采用溶胶-凝胶法在Pt/Ti/SiO2/Si基片上制备了（Nd,Bi）4Ti3O12薄膜。将薄膜于空气中分别进行每1层、每2层、每3层500℃预退火10 min,最后于氮气氛中680℃退火30 min。结果表明：预退火工艺对薄膜的结构和铁电性能都有影响：每一层预退火处理的薄膜具有较大的剩余极化值和最小的矫顽场（2Pr=47.8μC/cm2,2Ec=254 kV/cm）。所有薄膜都呈现良好的抗疲劳特性。     

Ferroelectric properties of Bi_(3.25)La_(0.75)Ti_(3)O_(12) thin films prepared by sol-gel method

The Bi3.25La0.75Ti3O12 thin films were fabricated on the Pt/Ti/SiO2/Si substrates using sol-gel method. The structure and morphology of the films were characterized us-ing X-ray diffraction and atomic force microscopy. The thin films showed a perov- skite phase and dense microstructure. The 2Pr and 2Vc of the Bi3.25La0.75Ti3O12 thin films annealed at 700℃ were 18.6 μC/cm2 and 4.1 V, respectively, under an applied voltage 10 V. After the switching of 1×1010 cycles, the Pr value decreased to 90% of its pre-fatigue values. The films showed good insulating behavior according to the test of leakage current. The dielectric constant and the dissipation factor of the Bi3.25La0.75Ti3O12 thin films were about 176 and 0.046 at 1 kHz, respectively.     

PECVD工艺参数对SiO_2薄膜光学性能的影响

为探索利用等离子体增强化学气相沉积(Plasma Enhanced Chemical Vapor Depo-sition,PECVD)技术制作光学薄膜的有效方法.以SiH4和N2O作为反应气体,通过采用M-2000UI型宽光谱变角度椭圆偏振仪对制作样片进行测试,分析了薄膜沉积过程中的不同的工艺参数对SiO2薄膜光学性能的影响.实验结果表明:在PECVD技术工作参数范围内,基底温度为350℃,射频功率为150 W,反应气压为100 Pa时,能够沉积消光系数小于10-5,沉积速率为(15±1)nm/min,折射率为(1.465±0.5)×10-4的SiO2薄膜.     

纳米晶Ba（Zr0．2Ti0．8）O3薄膜的外延生长与介电特性

用脉冲激光沉积工艺在半导体（001）SrTiO3：ω（Nb）=1．0％单晶基片上,外延生长出Ba（Zr0.2Ti0.8）O3（简称BZT）介电薄膜．在650℃原位退火10min,薄膜为（001）外延生长的晶粒．薄膜的晶化特征与表面形貌用薄膜X-ray衍射仪和原子力显微镜测量完成．BZT薄膜（002）峰的半峰宽只有0．72°,说明薄膜晶化良好;薄膜的平均晶粒为90nm,表面均方根粗糙度为4．3nm,说明薄膜表面平整．在室温、100kHz和500kV／cm条件下,BZT的最大介电常数和调谐百分率分别达到317和65％．     

溶胶凝胶法制备介孔五氧化二钽薄膜

以五氯化钽为反应前驱体,三嵌段两性聚合物P123做天然模板,用溶胶凝胶法制备出了介孔五氧化二钽薄膜．经过SEM检测分析,薄膜厚度约为200nm．XRD研究结果表明,制得的薄膜具有明显的介孔结构,经TEM检测可以观察到孔洞结构;得到的五氧化二钽薄膜经过400℃煅烧1h,介孔结构仍然得到保留．