A Room Temperature Two-Step Electrochemical Process for Large Area Nanocrystalline Ferrite Thin Films Deposition

In this paper, we present a room temperature two-step electrochemical process for the deposition of large area (∼10 cm²) nanocrystalline ferrite thin films. As an example, the optimized conditions for the deposition of copper, nickel and cobalt ferrites on different conducting substrates and their physical properties are reviewed. The films are spinel in crystal structure and well adherent to the substrates. The electrical and magnetic properties of the films after annealing are comparable to the properties obtained with the films formed with other physical and chemical techniques.     

NiZn铁氧体靶材及薄膜的磁性能和微观结构

首先采用固相反应法制备NixZn1-xFe2O4铁氧体靶材(x=0.2～0.8),研究了Ni取代量对靶材性能的影响;并选用Ni0.5Zn0.5Fe2O4靶材,采用射频磁控溅射法在Si(100)基片上制备了NiZn铁氧体薄膜.靶材样品的分析结果表明,随Ni含量增加,样品的X射线衍射峰向高角方向移动,晶格常数和平均晶粒尺寸都单调减小;当x=0.5～0.6时,NixZn1-xFe2O4铁氧体饱和磁感应强度Bs较高,矫顽力Hc较小.薄膜样品的分析结果表明,制备的薄膜经800℃退火后,呈尖晶石结构,并沿(400)方向择尤取向;薄膜的饱和磁化强度Ms和面内矫顽力Hc分别为310kA/m和8.833kA/m.     

Preparation of Barium Strontium Titanate Thin Film by Spray Deposition

Barium strontium titanate ((Ba,Sr)TiO 3 ; BST) thin films were prepared on platinum-coated silicon substrates using spray deposition. The spray condition (substrate temperature and chamber pressure) dependence on surface roughness for the fired BST thin films was investigated. We obtained BST films thinner than 100 nm on the following properties. Average roughness (Ra) and peak-to-valley value (Rmax) were 3.9 and 130 nm. Dielectric constant and dissipation factor at 1 kHz were 250 and 1.6%. These excellent properties were obtained with even thickness. This method is considered to be advantageous for use with electronic devices that have thin dielectric layers, which make for thin films.     

PZT Thin Film Bi-Layer Devices for Phase Controlled Actuation in MEMS

A potential application for ferroelectric thin films is micro positioning and actuation. For using PZT films as micro-actuators it is desirable to have film thicknesses of comparable size to the underlying structure. The amount of actuation possible is determined by a number of factors: the piezoelectric coefficient d ₃₁, geometric factors and the compliance of both the actuator and cantilever and the electric field across the film. Using a bi-layer should therefore increase the amount of actuation for a given drive voltage. Bi-layer devices can also be driven at constant voltage, and their actuation varied by the phase difference of the drive voltage between the two layers. PZT films of thickness 0.5 m have been deposited as a bi-layer. Micro-actuators have been fabricated using these structures, their electric properties measured and their electro-mechanical properties characterised and evaluated using optical beam deflection.     

Photoluminescence of ZnO:Ga Thin Films Fabricated by Pulsed Laser Deposition Technique

Highly c-axis oriented Ga-doped ZnO films (GZO) have been grown on sapphire (0001) substrates by pulsed laser deposition (PLD) method. Photoluminescence (PL) spectra indicate that Ga atoms have a large effect on the luminescent properties of ZnO films. PL spectra of GZO films show near band edge (NBE) emissions and broad orange deep-level emissions. The NBE emission shifts to higher energy region and the intensity decreases with the increase of Ga concentration. The blue shift of NBE emission results from Burstein-Moss effect. The quenching of NBE emission is ascribed to the noradiative recombination. The orange emission is related to the oxygen vacancies.     

Effect of Pyrolytic Film Thickness on the Texture Evolution of PZT Thin Films

This paper describes the effects of pyrolysis temperature and film thickness before annealing on the orientation and microstructure of the lead zirconate titanate (PZT) thin films prepared by chemical solution deposition method (CSD). Different thickness of the pyrolytic films were obtained by repeating deposition and pyrolysis with different times. The orientation and microstructures of the PZT thin films were characterized by X-ray diffractometry (XRD) and field-emission scanning electron microscope (SEM). The results show that the thickness of the pyrolytic films was the principal factor that affects the crystalline structures in PZT thin films.     

喷射沉积法Cu-9Ni-6Sn合金的组织与性能研究

用硬度测量仪、光学显微镜、电子探针、X射线衍射仪和透射电子显微镜研究了喷射沉积Cu-9Ni-6Sn合金的相组织以及时效过程的组织变化和时效强化,并与熔铸法制备的同种合金进行对比。结果表明,喷射沉积法能优化合金组织,有效地抑制Sn的偏析;Spinodal分解和亚稳相γ′是形成合金时效强化的主要原因;冷变形能加速合金时效强化。     

Ferroelectric SrBi 2 Nb 2 O 9 Thin Films by Aqueous Chemical Solution Deposition

SrBi 2 Nb 2 O 9 (SBN) thin films on a Pt/Ti/SiO 2 /Si substrate were prepared by aqueous chemical solution deposition. The precursor solution was synthesized by means of an 'aqueous solution-gel method', starting with stable, inexpensive and easily available inorganic salts which are dissolved in an aqueous solution of chelating or coordinating ligands (acetates and citrates). Afterwards the synthesized precursor was spin-coated. However, problems arose as a consequence of insufficient 'wetting' of the substrate surface by the aqueous solution (poor film-substrate adhesion). Instead of improving surface adhesion by the addition of a surface-wetting reagent, a new strategy was developed: prior to spin-coating the platinum surface characteristics were modified using a UV/ozone technique. In this way the precursor solution was not chemically changed. Wetting/wettability was verified by means of contact angle measurements. A uniform, three-layer thin film with a total thickness of about 200 nm was obtained after thermal treatment, as could be verified using SEM and XRD.     

GMR读磁头用面内取向CoCrPt永磁薄膜的结构与性能

用磁控溅射的方法在Cr1-xWx衬底上制备了GMR读磁头中用来提供水平偏置磁场的易轴水平取向的CoCrPt合金薄膜.研究了Cr1-xWx衬底(200)织构与W含量之间的关系,沉积在CrW衬底上的CoCrPt合金薄膜微结构及磁性能,以及CoCr中间层的添加对CoCrPt合金薄膜生长出面内取向的()织构的影响及磁性能的影响.实验结果表明,CoCr中间层的引入对CoCrPt合金薄膜易磁化轴的面内取向起到了十分关键的作用.     

The Dielectric Properties for Yttrium Doped SBT Thin Films Prepared by Sol-Gel Method

In this work, Sr_0.5Ba_0.5Ti_1-zY_zO₃ (SBT) thin films were prepared on a Pt/SiO₂/Si substrate by sol-gel process. The microstructures of SBT thin films were examined by IR, XRD and TEM. The influences of Y on the microstructure and dielectric properties of Sr_0.5Ba_0.5Ti_1-zY_zO₃ thin films were studied. It is found that tetragonal perovskite crystal grains existed in SBT thin films. Increasing Y doping has a clear effect on the grain size of SBT. It is found that the proper Y doping content decreases dielectric loss for SBT thin films.     

Review: Deposition of Ceramic Thin Films at Low Temperatures from Aqueous Solutions

Many techniques for the synthesis of ceramic thin films from aqueous solutions at low temperatures (25–100°C) have been reported. This paper reviews non-electrochemical, non-hydrothermal, low-temperature aqueous deposition routes, with an emphasis on oxide materials for electronic applications. Originally used for sulfide and selenide thin films, such techniques have also been applied to oxides since the 1970's. Films of single oxides (e.g., transition metal oxides, In₂O₃, SiO₂, SnO₂) and multicomponent films (doped ZnO, Cd₂SnO₄, ZrTiO₄, ZrO₂-Y₂O₃, Li-Co-O spinel, ferrites, perovskites) have been produced. The maximum thicknesses of the films obtained have ranged from 100 to 1000 nm, and deposition rates have ranged from 2 to 20,000 nm/h. Compared to vapor-deposition techniques, liquid-deposition routes offer lower capital equipment costs, lower processing temperatures, and flexibility in the choice of substrates with respect to topography and thermal stability. Compared to sol-gel techniques, the routes reviewed here offer lower processing temperatures, lower shrinkage, and (being based on aqueous precursors) lower costs and the potential for reduced environmental impact. This review emphasizes the influence of solution chemistry and process design on the microstructures and growth rates of the films. The current understanding of the mechanisms of film formation is presented, and the advantages and limitations of these techniques are discussed.     

Lead Zirconate Titanate Film Formation Technology with Use of Spray Coating Method

This paper presents a three-dimensional microfabrication and integration technology for MEMS smart materials that utilizes a spray coating method. Spray coating is shown to be most effective for additional deposition on non-planar surfaces. PZT films were formed both on flat and uneven surfaces at a thickness of about 1μ m. Perovskite structures were formed with suitable heat treatment and ferroelectric P-E hysteresis loop was also obtained. This paper is the first report from our group and other researchers on the deposition of smart materials for MEMS using a spray coating method. Spray coating has been proposed as an effective three-dimensional coating method which can be used to deposit piezoelectrics, pyroelectrics, magnetics, etc. for sensors and actuators. The hydrophilic and hydrophobic properties between the substrate surface and ejected liquid are most essential process factors in the spray coating method for improving the film growth conditions.     

Optimum Reflection-Type Phase Shifter Using (Ba,Sr)TiO3 Thin Film

In this paper, in order to obtain a large differential phase shift with a little change in applied voltage, a ferroelectric reflective load circuit has been designed on top of barium strontium titanate (Ba,Sr)TiO₃ [BST] thin film. The design of the ferroelectric reflection-type phase shifter is based on a reflection theory of terminating circuit, which has a reflection-type analogue phase shifter with two ports terminated in symmetric phase-controllable reflective networks. To achieve large amounts of phase shift in low bias-voltage range, the effects of change of capacitance and transmission line connected with two coupled ports of a 3-dB 90° branch-line hybrid coupler have been investigated. A large phase shift with a small capacitance change in the parallel terminating circuit has been demonstrated in the paper.     

磁头用软磁Fe-Co-Al-O薄膜的结构和性能

用射频磁控溅射方法制备了记录磁头用FeCoAlO薄膜软磁材料,与FeCo合金薄膜相比,FeCoAlO薄膜的软磁性能有明显改善.(Fe72Co28)100-x(Al2O3)x薄膜的饱和磁感应强度Bs在x=3.1～5.9范围内基本保持恒定,当x>5.9时,饱和磁感应强度急剧降低;其矫顽力随Al2O3含量的增加迅速降低.当Al2O3含量为5.9时,薄膜的矫顽力由未加Al2O3时的3580A/m下降到Hce≈418A/m,Hch≈289A/m,饱和磁感应强度Bs=2.15T;薄膜还表现出良好的高频特性,当频率f≤1.0GHz时,磁导率μ≈500.结构分析表明,薄膜中软磁性能的改善和添加Al2O3导致的晶粒细化有关.     

Non-Linear Imprint Behavior of PZT Thin Films

Ferroelectric thin film capacitors are promising candidates for non-volatile ferroelectric Random Access Memories (FeRAM's) as they exhibit a switchable polarization. There are three important failure-mechanisms influencing the performance of these capacitors and disturbing the long-term stability and reliability under operation conditions fatigue, retention, and imprint. The imprint effect of lead zirconate titanate (PZT) thin films was investigated in this paper. Establishing and maintaining a polarization state leads to a shift of the hysteresis loop on the voltage axis and also to a loss of polarization. The voltage shift as well as the loss of polarization can cause a failure of the ferroelectric memory cell (read and write failure). The experimental results obtained on PZT films are discussed in view of the predictions of imprint models proposed in the literature.     

钡铁氧体薄膜的研究及应用

钡铁氧体薄膜有着良好的磁性能。介绍了钡铁氧体薄膜的基本制备方法,综述了溶胶-凝胶法、对向靶溅射法、脉冲激光沉积法和射频溅射法的最新研究状况,结合最新文献论述了钡铁氧体薄膜的几种典型的表征方法,对钡铁氧体薄膜的应用领域进行了总结,并讨论了钡铁氧体薄膜目前存在的问题及发展趋势。     

Pb(Mg1/3Nb2/3)0.97Ti0.03O3 Ferroelectric Thin Films, Deposited by Laser Ablation on TiN Bottom Electrodes

Pb(Mg_1/3Nb_2/3)_0.97Ti_0.03O₃ (PMNT) polycrystalline thin films were deposited on Titanium Nitride electrode at different temperatures by laser ablation, using a wavelength of 248 nm. The morphology of the films was analyzed by scanning electron microscopy (SEM). The nature of the ferroelectric layer-electrode interface is studied by transmission electron microscopy (TEM) as well as the effect of its characteristics in the performance of the multilayer system. The influence of the annealing temperature on the dielectric properties was studied by hysteresis and fatigue measurements.     

Aging and Annealing Effects of ZnO Thin Films on GaAs Substrates Deposited by Pulsed Laser Deposition

Zinc oxide (ZnO) thin films were deposited on GaAs (100) substrates at different temperatures in the pulsed laser deposition (PLD) system. From the measurements of X-ray diffraction (XRD) at room temperature, 300–500°C were found to be good condition for the crystallization of the thin films. From the photoluminescence (PL) measurements, 500°C was found to be the optimized temperature for its optical property. Samples grown at 100, 200, 300, and 400°C showed near band-edge (NBE) emissions and deep-level emissions. The intensity of deep-level emissions decreased as time goes on, which is believed to originate from oxygen vacancies or zinc interstitials in thin films. While for the sample grown at 500°C, bright NBE emissions were observed at room temperature, and no deep-level emissions observed. This means that the high-optical-quality thin film was grown at 500°C. At the same time, annealing process of ZnO thin films grown at room temperature was carried out in PLD chamber. It was found that the annealing temperature of 600°C has strong effects on its PL. Aging and annealing effects in ZnO thin films grown on GaAs substrates by PLD were observed for the first time.     

Studies of ZnO Thin Films On Sapphire (0001) Substrates Deposited by Pulsed Laser Deposition

ZnO thin films are deposited on sapphire (0001) substrates at different temperatures in the pulsed laser deposition (PLD) system. By measurements of X-ray diffraction (XRD), atomic force microscopy (AFM), and Photoluminescence (PL) at room temperature, fabrication temperatures higher than 400C is found to be the optimum condition for the structural and optical properties of ZnO thin films. With the increase of the fabrication temperature, the grain size becomes bigger and the thin film becomes more homogeneous. In order to get the high-quality ZnO thin film at low temperature, ZnO thin films are deposited at room temperature and annealed in a rapid thermal annealing (RTA) system. It is found that the optical property of the thin film can be greatly improved by annealing in RTA system.