(Pb,La)TiO3/LaNiO3异质结薄膜的漏电流特征

采用溶胶-凝胶法(sol-gel),以LaNiO3(LNO)为底电极在/Pt/Ti/SiO2/Si(100)衬底上生长了(Pb1-xLax)Ti1-x/4O3(x=28 mol%,简称PLT)薄膜.经过600℃快速退火.从而得到了多晶钙钛矿结构PLT薄膜.薄膜漏电流和电压极性有关,当在Pt电极或LNO电极施加负偏压时,在低电场作用下,Pt/PLT和PLT/LNO界面分别形成肖特基势垒和欧姆接触;在高电场作用下,Pt/PLT和PLT/INO界面的漏电流均呈现空间电荷限制电流导电机制.这是因为用金属氧化物LNO做底电极的缘故.     

PZT铁电薄膜的制备与性能

用sol-gel法在Al2O3基片上制备PZT铁电薄膜.研究发现,制备PZT溶胶时加入乙酰丙酮可以提高溶胶的稳定性,并抑制热处理时薄膜上裂纹的产生.薄膜在700℃热处理可以得到单一的钙钛矿结构;低温慢升高温快升的升温制度可以减少薄膜的开裂.Pt底电极的加入有利于钙钛矿相的形成.PZT薄膜电滞回线形状和Pr、Ec等随着热处理制度和薄膜厚度的变化而变化.     

退火温度和匀胶速率对SrBi_(3.88)Nd_(0.12)Ti_4O_(15)薄膜铁电性能的影响

用溶胶-凝胶法在Pt/Ti/ SiO_2/ Si基片上制备了SrBi_3.88 Nd_0.12 Ti_4O_(15)铁电薄膜材料,研究了退火温度和匀胶速率对铁电薄膜材料结构、铁电性能的影响.退火温度为750 ℃、匀胶速率为3000 r/min薄膜样品为纯的铋层状钙钛矿结构且没有其它杂相出现,a轴取向的晶粒较多,铁电性能较好,剩余极化强度和矫顽场分别为2P_r=26.7 μC/cm~2、2E_c=80 kV/cm.     

紫外光辐照Bi_(4-x)Nd_xTi_3O_(12)薄膜制备工艺

以Pt(111)/Ti/SiO_2/Si为基片,采用溶胶凝胶法,通过紫外光辐照钕掺杂钛酸铋(Bi_(4-x)Nd_xTi_3O_(12), x=0.25, 0.75)胶体,分别采用电泳沉积和甩胶沉积制备薄膜,并对比了制备的薄膜质量.通过差热-热重分析(DSC-TG)、X射线衍射(XRD)、原子力显微镜(AFM)等技术手段对Sol-Gel法制备的BNT薄膜进行了表征.研究结果表明,经紫外光辐照和电泳沉积制备的Bi_(4-x)Nd_xTi_3O_(12) (x=0.25, 0.75) 薄膜于300 ℃煅烧有机物,500 ℃随炉热处理,可得到均匀致密且(117)择优取向的钙钛矿相BNT薄膜.     

退火温度对钴铁氧体薄膜结构和性能的影响

采用溶胶-凝胶法结合匀胶旋涂工艺在复合基片(Pt/Ti/SiO2/Si)上制备了钴铁氧体(CoFe2O4)薄膜,利用XRD、SEM、VSM分析了薄膜的微结构以及磁性能,研究了不同退火温度对钴铁氧体薄膜的结构和磁性能的影响.结果表明,钴铁氧体在500℃时开始形成尖晶石相.随着退火温度的增高,钴铁氧体晶粒逐渐长大,饱和磁化...     

ZrW2O8薄膜的制备及热膨胀性质

采用溶胶-凝胶技术结合退火工艺在Pt(111)/Ti/SiO2/Si(100)基片上制备ZrW2O8薄膜,并研究了退火温度、退火时间对薄膜的影响.利用X射线衍射(XRD)及扫描电镜(SEM)对薄膜的物相及表面形貌进行表征;利用变温XRD研究薄膜的热膨胀性能.薄膜的变温XRD结果表明,在室温～700℃温度范围内,随着温度的升高,(211)和(310)晶面间距变小,其热膨胀系数为负值,而(332)晶面间距随温度升高变大,显示出正膨胀性质.这表明ZrW2O8薄膜材料的热膨胀性能是各向异性的.     

铁酸铋薄膜的溶胶-凝胶法制备及电性能研究进展

铁酸铋是唯一一种在室温下存在的单相多铁材料,因其具有较高的铁电居里温度、较大的剩余极化强度、较小的禁带宽度和多铁特性,受到国内外的广泛关注。溶胶-凝胶法是制备铁酸铋薄膜的一种常见方法。综述了近年来溶胶-凝胶法制备铁酸铋薄膜的研究进展,详细阐述了制备工艺参数(前驱液、退火温度、退火气氛、底电极)与掺杂对铁酸铋薄膜电性能的影响;分析了不同制备工艺导致薄膜电性能出现差异的原因;归纳、总结出了目前溶胶-凝胶法制备铁酸铋薄膜的较佳工艺条件;最后,指出了亟待解决的问题。     

MOCVD制备的Pt/C薄膜的结构与性能研究

以乙酰丙酮铂为前驱体,采用金属有机化合物化学气相沉积(MOCVD)法在石英及YSZ基体上制备Pt/C薄膜,研究了Pt/C薄膜的结构和电化学性能.沉积过程中通入一定量的氧气可以大幅降低Pt/C薄膜中的含C量,含C较高的Pt/C薄膜的XRD谱线低而宽,具有非晶态衍射特征.在500℃测量温度下,以Pt/C薄膜为电极的YSZ氧气浓差电池的电动势及电流输出高于传统的Pt电极.     

热处理工艺对(111)取向Pt薄膜物相与结构的影响

采用射频磁控溅射法成功制各了(111)取向的Pt薄膜.在研究退火工艺对Pt薄膜(111)取向生长的影响基础上,着重研究了退火工艺对Pt薄膜与缓冲层Pr薄膜间的互扩散及薄膜物相、结构的影响规律.结果表明:250℃保温5至25小时,Pt薄膜沿(111)择优取向生长,但保温时间对取向生长的影响不大,此时薄膜为立方结构;当500℃再分别保温2h和4h时,最初沿(111)取向生长的Pt薄膜与Pr薄膜发生互扩散现象,生成BFe结构的PrPt相,保温2h时,除生成PrPt相外,还可能存在一定量的取向Pt,保温4h时,薄膜中只存在PrPt相.本实验为制备(111)强烈取向Pt薄膜开拓了一条新的工艺及方法,同时为控制Pt薄膜的结构与性能、进行开发应用提供了实验依据.     

退火温度对(Pb_(0.5)Sr_(0.5))TiO_3薄膜光学性能的影响(英文)

以三水醋酸铅、醋酸锶、钛酸丁酯为原料,乙二醇甲醚、去离子水、乙酰丙酮做溶剂。用溶胶-凝胶法制备(Pb0.50Sr0.50)TiO3 (PST)前驱体溶液,通过旋涂工艺在石英玻璃基片上沉积 PST 薄膜。薄膜经 650 至 800 ℃退火 30 min,升温速率为 3℃/min。不同温度晶化的 PST 薄膜用 X 射线衍射测量其晶体结构,用原子力显微镜观测其表面形貌。不同温度退火薄膜的光学透射谱用双光束紫外-可见光分光光度计测量。薄膜的吸收边,即带隙能可以根据直接跃迁估计。650、700、 750 和 800℃退火的薄膜样品的直接带隙能分别为 3.74、3.75、3.76 和 3.75 eV。     

Preparation and characterization of sol–gel derived (1 0 0)-textured Pb(Zr,Ti)O3 thin films: PbO seeding role in the formation of preferential orientation

Lead zirconate titanate (PZT) thin films with a composition near the morphotropic phase boundary region were deposited onto Pt(1 1 1)/Ti/SiO₂/Si(1 0 0) substrates using a sol–gel method. A seeding layer was introduced between the most underlying surface of the PZT film and the platinum electrode surface to control the texture of the PZT thin film. The lead oxide seeding layer resulted in the formation of a single-phase perovskite and absolutely (1 0 0)-textured PZT film. SEM, XRD, XPS, and AES were used to characterize the evolution of the lead oxide layer and the PZT thin films. The growth kinetic mechanism of the (1 0 0)-textured PZT thin films was proposed phenomenologically. The ferroelectric and piezoelectric properties of the PZT films were also evaluated and discussed in association with different preferential orientations.     

Interface between electrode and PZT memory device

PbZrTiO₃ (PZT) is one of the most promising ferroelectric materials for ferroelectric random access memory (FeRAM). But, there is a problem that the PZT ferroelectric properties are degraded with platinum (Pt) electrodes after annealing in a hydrogenous atmosphere during LSI fabrication. This degradation has been attributed to the catalytic nature of Pt, which dissociates H₂ into protons which then migrate into the PZT and reduce it at elevated temperature. In this theory, it is unclear how Pt and PZT physically interact at the interface. Also, the mechanism concerning the generation of an interfacial layer of oxygen vacancies has not been addressed, which creates some ambiguity in the model. We researched the interface using secondary ion mass spectroscopy (SIMS) and field-emission type transmission electron microscopy (FE-TEM) in order to more clearly understand its impact on the degradation mechanism. We have verified atomically that annealing a Pt/PZT/Pt capacitor results in Pb diffusion from the PZT into the Pt electrode and Pt diffusion from the electrode into the PZT. We next verified that the interdiffusion is not a usual thermal interdiffusion process, but appears rather to be generated by the reaction with hydrogen on both top and bottom Pt electrodes. Finally, we present a model of how the effects of hydrogen reduction combine with the Pt catalysis to form oxygen vacancies. Lead and Pt interdiffuse easily through these vacancies at both interfaces. The model presented here can predict the distribution of vacancies and demonstrates the limitations of the recovery anneal. It also supplements our understanding of the degradation process and provides additional credibility to the above theory.     

Structural, ferroelectric and dielectric properties of In2O3:Sn (ITO) on PbZr0.53Ti0.47O3 (PZT)/Pt and annealing effect

Ferroelectric indium tin oxide (ITO) on PbZr_0.53Ti_0.47O₃ (PZT)/Pt structure, prepared by RF sputtering onto SiO₂/Si substrates, is studied in order to investigate the effect of ITO as a top electrode in these systems. X-ray diffraction, scanning electron microscopy (SEM) and atomic force microscopy (AFM) experiments were performed to study the structure and the surface morphology of the samples. From X-ray diffraction, we observe that the ITO thin film grows with the (1 1 1) texture and the peaks attributed to PZT are all from the perovskite phase. The average roughness (RMS) of the PZT surface is found to be 1.650 nm from AFM experiment. The ferroelectric and dielectric properties were inferred from polarization hysteresis loops, capacitance and dielectric constant measurements. These properties have been compared to those of the widely studied Pt/PZT/Pt system prepared under the same conditions. The effect of ITO/PZT/Pt annealing has been studied. Annealing at 400 °C leads to 13% increase in the dielectric constant ?_r.     

Highly (1 0 0)-textured Pb(Zr0.52Ti0.48)O3 film derived from a modified sol–gel technique using inorganic zirconium precursor

Highly (1 0 0)-textured Pb(Zr_0.52Ti_0.48)O₃ films have been prepared on platinized silicon substrate by a modified sol–gel technique using inorganic zirconium precursor. The X-ray diffraction analysis on the crystallinity and texture evolution of sol–gel lead zirconate titanate (PZT) films revealed that the films were well crystallized to perovskite phase when annealed at 550 °C, and that highly (1 0 0) preferred orientation dominated in the PZT films after annealed at 650 °C. The (1 0 0)-oriented PZT film exhibited the remnant polarization of 26.3 μC/cm² and the coercive field of 100 kV/cm.     

Substrate heterostructure effects on interface composition,microstructure development and functional properties of PZT thin films

Platinum- and (La_0.8,Sr_0.2)MnO₃ (LSMO)-terminated silicon substrates were used for the liquid-phase deposition of Pb(Zr_0.52,Ti_0.48)O₃ (PZT) thin films. Different layer thicknesses ranging from 100 to 600 nm were processed by sequential coating. Characterization of the films involved X-ray diffraction, atomic force microscopy and X-ray photoelectron spectroscopy (XPS) combined with depth profiling to probe the interface composition. The films deposited on Pt exhibit an intermetallic layer, Pt_xPb, after annealing at 500 °C in air. This film has been used to establish the XPS signature of the intermetallic phase which consists of a negative shift of the peak position of Pt(4f) due the electron transfer from Pb to Pt. In all cases pure phase perovskite thin films were obtained after short annealing at 700 °C. XPS depth profiling shows unambiguously the existence of an intermetallic layer, Pt_xPb, of approximately 10 nm at the interface between Pt and PZT, while an interdiffusion layer of ～30 nm was observed between LSMO and PZT. The impacts of interfacial layers on microstructure development and functional properties translate in the formation of specific textures, i.e. a pronounced (1 1 1)-texture on Pt due to lattice matching between (1 1 1)-PZT and (1 1 1)-Pt_xPb, and a random film orientation on LSMO, and a substantial thickness dependence of the dielectric and ferroelectric properties, though specific behaviors were observed for the two different substrate heterostructures.     

离子束溅射制备Pt/C催化电极材料的结构和电化学性能

采用离子束溅射技术制Ｐｔ／Ｃ催化电极,降低了电极耗铂量至０．１９ｍｇ／ｃｍ＾２,电极具有良好的电化学性能。研究了在不同碳质载体材料上用不同沉积条件制备的Ｐｔ／Ｃ电极的电化学性能。     

Effect of Annealing on the Morphology,Structure and Photoelectric Properties of AZO/Pt/FTO Trilayer Films

Aluminum-doped zinc oxide/platinum/fluorine-doped tin oxide(AZO/Pt/FTO) trilayer films were prepared by sputtering 5-nm-thick Pt layers and 150-nm-thick AZO layers in sequence on commercial FTO glass.The effects of onestep annealing and layer-by-layer annealing on the morphology,structure and photoelectric properties of the AZO/Pt/FTO trilayer films were comparatively analyzed.It is found that the both annealing approaches increased the grain size and improved the crystallinity of the films,leading to enhancement in transmittance and conductivity.However,layer-by-layer annealing led to the formation of quasi-continuous or continuous AZO layers,different from the sparsely distributed AZO particles brought about by one-step annealing,resulting in excellent optical and electrical properties.Specifically,after layer-by-layer annealing at 400 ℃ for both Pt and AZO layers,the AZO/Pt/FTO trilayer film showed an increase in average transmittance from 71.3% to 85.3% and a decrease in sheet resistance from 7.5 to 5.6 Ω/□,leading to the highest figure of merit of 3.64 × 10~(-2) Ω~(-1).     

PZT铁电薄膜电极材料研究进展

近几年,PZT铁电存储器的商业应用受到了广泛关注,但PZT电容器的疲劳现象已成为其应用的严重障碍,变换电极是改善PZT电容器抗疲劳特性的有效方法.系统地介绍了PZT铁电薄膜用电极材料的结构、性能及其特点,比较了不同电极材料对PZT铁电薄膜结构及铁电性能的影响,并对导电金属氧化物电极改善抗疲劳特性的机制进行了一定的分析,提出了电极材料的主要问题和发展方向.     

Effects of la concentration on the texturing and the electrical properties of sol-gel derived PLT thin films

Lanthanum doped lead titanate (PLT) thin films consisting of different La concentrations were fabricated on Pt/Ti/SiO₂/Si using sol-gel method. The films were dried at 440°C for 5 min and fired at 600°C using rapid thermal annealing (RTA) for 1min. The preferred orientation (texturing) and the morphology of the PLT film were changed with La concentration and a possible cause of the texturing has been discussed. The effects of La doping to the Lead titanate films on the dielectric constants, P-E hysteresis loop and pyroelectric coefficient were measured and discussed.     

The effect of multilayer structure on magnetic properties of FePt thin films

The Fe/Pt multilayer films with different structures were deposited by RF magnetron sputtering on glass substrates, and the L1₀-FePt films were obtained after theas-deposited samples were subjected to vacuum annealing at various temperatures. Results show that the Fe/Pt multilayer structure can effectively reduce the ordering temperature of FePt film, and the in-plane coercivity of [Fe (5.2 nm)/Pt (5.2 nm)]₇ multilayers can reach 161.2 kA/m after annealed at 350 ℃ for 30 min. When Fe and Pt layer thickness is equal, the coercivity of the film is the largest. On the other hand, the different Fe-Pt crystalline phases such as Fe₃Pt and FePt₃ phases are formed after annealing when the thickness ratio of Fe/Pt deviates from 1 after annealing. When Fe and Pt have the same thickness, the thinner single layer gets the lower ordering temperature and the larger coercivity.