新型PST铁电薄膜的制备及其电性能研究

PST铁电薄膜是一种具有优良铁电、热释电和介电等性能的铁电材料.该材料在红外探测器、红外焦平面阵列、热成像器件、非易失性铁电存储器和大容量电容器等方面具有广泛的应用.PST铁电薄膜的制备方法多种多样,各具优缺点,不同的制备工艺对薄膜的性能有影响.叙述了PST铁电薄膜的制备技术、电性能和在热释电红外探测器方面的应用.     

（Pb1-x Srx）TiO3铁电薄膜电滞回线的测试分析

采用磁控溅射法制备了PST薄膜,讨论了其制备工艺并着重对其电滞回线进行了测试分析.从测试结果来看,其饱和极化强度Ps典型值为19.0μC/cm2,剩余极化强度为6.6μC/cm2,矫顽场强为16 kV/cm,热释电系数为10-4量级.表明所制备的PST薄膜具有较好的铁电性能.     

金属有机化学气相沉积制备铁电薄膜材料研究进展

铁电薄膜是一类重要的功能材料,是近年来高新技术研究的前沿和热点之一.金属有机化学气相沉积(MOCVD)是制备铁电薄膜的一种重要方法.综述了金属有机化学气相沉积法制备铁电薄膜的历史、原理、工艺参数、特点和采用此方法制备出的某些材料的铁电性能.     

磁控溅射制备(Pb1-xSrx)TiO3系铁电薄膜的实验研究

钛酸锶铅((Pb1-xSrx)TiO3,PST)固溶体材料是一种性能优良的钙钛矿型铁电材料,其形成铁电相的温度较低,且易于和半导体工艺结合,应用潜力较大.本文采用磁控溅射法制备了PST薄膜,并初步研究了其介电和铁电特性.结果表明,磁控溅射得到的PST薄膜必须进行一定的热处理,才能使之转变为具有铁电性的钙钛矿结构的铁电薄膜.其介电特性与测试频率有关,试样的饱和极化强度可达19μC/cm2,剩余极化强度可达6.6μC/cm2,矫顽场强达16kV/cm,热释电系数达10-4C/m2*K量级,表明所制备的PST薄膜具有良好的铁电性.     

磁控溅射制备（Pb1—xSrx）TiO3）系铁电薄膜的实验研究

钛酸锶铅（Pb1-xSrx)TiO3,PST)固溶体材料是一种性能优良的钙钛矿型铁电材料,其形成铁电相的温度较低,且易于和半导体工艺结合,应用潜力较大,本采用磁控溅射法制备了PST薄膜,并初步研究了其介电和铁电特性,结果表明,磁控溅射得到的PST薄膜必须进行一定的热处理,才能使之转谈具有铁电性的钙钛矿结构的铁电薄膜,其介电特性与测试频率有关,试样的饱和极化强度可达19uC/cm2,剩余极化强度可达6．6uC/cm2,矫顽场强达16kV/cm,热释电系数达10^-4C/m2.K量级,表明所制备的PST薄膜具有良好的铁电性。     

PbSc0.5Ta0.5O3热释电材料及其红外探测器列阵

热释电红外探测器具有探测波长范围广、室温工作、无需致冷等优点。近年来，工作于介电方式下的PbSc0.5Ta0.5O3(PST)热释电材料由于具有热释电系数大，热释电探测优值高等特点，成为热释电应用研究的热点之一。本文综述了目前PST热释电陶瓷材料的介电，热释电性能及其探测器列阵的发展。由于小型化的要求，PST薄膜亦倍受关注，因此本文还对目前PST热释电薄膜的制备方法，薄膜的热释电、介电性能及薄膜型探测器结构和发展进行了概述。     

微弧氧化法及其在铁电薄膜制备中的应用

介绍了微弧氧化法的基本原理和工艺过程;综述了微弧氧化法制备铁电薄膜的发展历程及最新研究进展;讨论了目前微弧氧化制备铁电薄膜过程中存在的主要问题;提出了合理选择溶液体系和溶液浓度,研究工艺参数对薄膜表面形貌和铁电、介电性能的影响,提高薄膜表面质量是促进微弧氧化制备铁电薄膜技术发展的关键。     

铅过量PLZT铁电薄膜的制备及其电学性质研究

采用Sol Gel法 ,在Pt TiO2 Si基片上制备了具有不同铅过量 (0— 2 0mol% )的PLZT铁电薄膜。分析了薄膜的晶相结构 ,研究了铅过量对PLZT铁电薄膜的介电性能和铁电性能的影响。结果表明 ,各薄膜均具有钙钛矿型结构 ,且各薄膜均呈 (110 )择优取向。PLZT铁电薄膜的介电性能和铁电性能随铅过量的变化而改变。铅过量为 10mol%的薄膜具有最佳的的介电性能和铁电性能。     

磁控溅射制备(Pb_(1-x)Sr_x)TiO_3系铁电薄膜的实验研究

钛酸锶铅 ((Pb1 -xSrx)TiO3,PST)固溶体材料是一种性能优良的钙钛矿型铁电材料 ,其形成铁电相的温度较低 ,且易于和半导体工艺结合 ,应用潜力较大。本文采用磁控溅射法制备了PST薄膜 ,并初步研究了其介电和铁电特性。结果表明 ,磁控溅射得到的PST薄膜必须进行一定的热处理 ,才能使之转变为具有铁电性的钙钛矿结构的铁电薄膜。其介电特性与测试频率有关 ,试样的饱和极化强度可达 19μC cm2 ,剩余极化强度可达 6 6 μC cm2 ,矫顽场强达 16kV cm ,热释电系数达10 - 4 C m2 ·K量级 ,表明所制备的PST薄膜具有良好的铁电性。     

锆钛酸铅铁电薄膜的制备及性能研究

本文用无机锆盐代替锆的醇盐，研究了溶胶－凝胶技术制备锆钛酸铅（简称ＰＺＴ）铁电薄膜的热处理工艺、结构和电性能。研究结果表明，在Ｓｉ单晶基片上制备的ＰＺＴ薄膜为钙钛矿型结构的陶瓷薄膜，其晶粒细小、致密，且具有良好的铁电性能，适合于制备铁电存贮器。     

脉冲激光沉积Ba0.5Sr0.5TiO3、Pb0.5Ba0.5TiO3和Pb0.5Sr0.5TiO3薄膜及其介电性质

采用脉冲激光沉积法,在Pt／Ti／SiO2／Si基底上分剐制备厚度为350nm的Ba0.5Sr0.5TiO3(BST)、Pb0.5Ba0.5TiO3(PBT)和Pb0.5Sr0.5TiO3(PST)薄膜并研究了它们的介电性质。XRD显示,在相同的制备条件下三者具有不同的择优取向,PST具有(110)择优取向,PBT具有(111)择优取向,而BST则是混合取向。SEM显示三者样品表面均匀致密,颗粒尺寸大约在50nm至150nm之间。PST与BST、PBT相比有更高的介电常数,在频率为10kHz时,分别为874、334和355,而损耗都较低,分别为0．0378、0．0316和0．0423,同时PST漏电流也是最小的。测量薄膜的C-V特性扣铁电性能表明室温下BST呈现的是顺电相,PST和PBT则呈铁电相。本文也测量了薄膜在不同频率下的介电温度特性,BST、PBT和PST均表现出频率弥散现象,即随着频率的降低．居里温度降低而介电常数会升高。并测得BST和PST的居里温度分剐为-75和150℃。而PBT的居里温度在250℃以上。本文研究表明：与BST相比较,PBT的介电常数与之相近,漏电流较大;而PST具有高介电常数,较小的漏电流和较大的电容-电压调谐度,在相关半导体器件中的应用将有很大的潜力。     

影响磁控溅射制备PST/Si薄膜介电特性的几个因素

采用磁控溅射制备了Si基(Pb1-xSrx)TiO3(简称PST/Si)薄膜。测试表明,热处理工艺对PST/Si薄膜介电特性有着一定的影响,适当温度、适当时间的热处理可得到均匀致密的膜层及生长良好的晶粒,从而确保PST薄膜良好的介电特性。样品上电极材料对介电特性也有重要影响。Al较Au电极易氧化,从而易在其与PST薄膜的界面形成一氧化层,增加了串联电阻,导致介电损耗总体上要低。工作频率对材料的介电弛豫特性及漏电导等也会产生影响。     

Effect of Zn doping on structure and ferroelectric properties of PST thin films prepared by sol–gel method

(Pb _y Sr_1−y )Zn _x Ti_1−x O_3−x thin films were prepared on ITO/glass substrate by sol–gel process using dip-coating method. The phase structure, morphology and ferroelectric property of the thin film were studied. All the thin films show the typical perovskite phase structure. Both the crystallinity and c/a ratio of the perovskite phase increases initially and then decreases gradually with doping Zn in the thin film. Ferroelectric properties of the Zn-doped PST thin films, including ferroelectric hysteresis-loop, remnant polarization and coercive force, decrease gradually with increasing Zn. And the effect of Zn on ferroelectric properties is more obvious in PST thin film with high content of Pb than that with low Pb although the high lead thin film exhibits high intrinsic ferroelectric properties.     

Amorphous ferroelectric thin film capacitive device for hydrogen detection

Hydrogen is a promising alternative energy source for next generation automobile engines that meet the concern of energy shortage and global environmental pollution. Hydrogen detection is an important associated technology to be developed. The recently developed amorphous ferroelectric thin film capacitive gas sensors with a largely improved sensitivity to hydrogen show a great potential for this associated technology. This review presents an overall picture of amorphous ferroelectric thin film hydrogen gas sensors. It focuses on the correlation among processing, microstructural evolution and electrical properties of amorphous ferroelectric thin films. An attempt is made to detail the hydrogen sensitivity and transient response of various prototype capacitive devices with respect to the quality of the films and the hydrogen kinetic processes in the Pd/ferroelectric heterostructure. Recent advances on the hydrogen interface-blocking model for amorphous ferroelectric gas sensors are also described.     

Effect of lattice-mismatch strain on the structural and dielectric properties of (Pb,Sr)TiO3 thin films grown by pulsed laser deposition

Pb_0.35Sr_0.65TiO₃ (PST) thin films have been fabricated on LaAlO₃ (LAO) and MgO substrates using the pulsed laser deposition technique. The microstructure characteristics of the films were examined by means of X-ray diffraction, atomic force microscopy, scanning electron microscopy and Raman spectroscopy, and the results indicate that the films are epitaxially grown and show good crystallinity. The dielectric constant dependence on DC bias voltage and temperature were measured in a planar capacitor configuration for these films. Compared to the PST thin film grown on LAO, the film grown on MgO showed a higher temperature of the capacitance maximum and a higher dielectric constant at zero bias. We explain the results by taking into account the lattice-mismatch strain between the substrate and the film. In contrast to the in-plane compressive strain induced by the LAO substrate, the in-plane tensile strain induced by the MgO substrate enlarges the unit cell of PST and enhances the magnitude of dipole moments, which increases the dielectric constant. These results indicate that a reasonable in-plane tensile strain could improve the dielectric properties of PST thin films.     

Preparation of high (100) oriented PST thin films deposited on PT/Tb inducing layer by rf-sputtering method

Tb doped PbTiO₃ (PT) thin films with (001)/(100) preferred orientation are prepared by sol-gel method. High (100) oriented Pb_0.4Sr_0.6(Ti_0.97Mg_0.03)O_2.97(PST) thin films are then deposited on the Tb doped PbTiO₃ inducing layer by rf-sputtering technique. The crystalline phase structure and orientation of the thin film are determined by X-ray diffraction. The dielectric properties of the thin films are measured by an Impedance Analyzer. Results show that the Tb doped PT films exhibit preferred orientation. The PST thin films deposited on substrate with and without PT inducing layer show (100) orientation and random orientation respectively. Higher (100) orientation appears in the PST thin films deposited on thinner inducing PT layer (one layer compare to more layers). A dielectric tunability of 39% is obtained in the PST thin film deposited on thinner PT inducing layer. It is a little higher than that deposited on thicker inducing layer.     

Ferroelectric films for non volatile-memory applications

Microelectronic applications of ferroelectric thin films have undergone a resurgence. Recent advances in deposition technologies and the achievement of bulk properties in thin films have enabled successful integration and fabrication of ferroelectric random access memories onto standard integrated circuits that combine high speed, complete non-volatility and extreme radiation hardness. Current research covers both the basic and applied areas in ferroelectric material science and semiconductor device development. In this talk the evolution of solid state memory devices in conjunction with silicon technology will be described, and the increasingly important role expected from ferroelectric materials highlighted. In coupling ferroelectric thin film processing with Si technology several new problems have to be resolved. The device physics and design, the material choice for ferroelectric memories, thin film preparation and characterization, and the problems of fatigue and retention will be discussed.     

结构设计对铁电薄膜系统电滞回线的影响

为制备符合Si集成铁电器件要求的高质量Si基铁电薄膜，采用溶胶—凝胶(sol—gel)工艺，制备了MFM及MFS结构的铁电薄膜系统，研究了不同结构及不同衬底对铁电薄膜系统铁电性能及电滞回线的影响，并对这些差异产生的主要影响因素进行了分析，在此基础上，提出并制备了Ag／Pb(Zr0.52Ti0.48)O3／Bi4Ti3O12／p—Si多层结构，该结构铁电薄膜系统的铁电性能及电滞回线的对称性有明显改善，有望应用于Si集成铁电器件。     

Structural evaluation of sol-gel derived lead strontium titanate diffusion barrier for integration in lead zirconate titanate transducer design

Sol-gel derived Pb₄₀Sr₆₀TiO₃ (PST) thin film has been investigated as a diffusion barrier for integrating in PbZr₃₀Ti₇₀O₃ (PZT) device structures on Si substrates. PST film was deposited on SiO₂/Si substrate and annealed at a relatively low temperature range of 550-600 °C producing a crack-free, smooth and textured surface. Following deposition on PST/SiO₂/Si template PZT thin film was crystallised exhibiting random grain orientations and an insertion of the bottom Pt/Ti electrode forming PZT/Pt/Ti/PST/SiO₂/Si stacks promoted the preferred PZT (111) perovskite phase. PZT (111) peak intensity gradually decreased along with slight increase of the PZT (110) peak with increasing annealing temperature of the buffer PST film. The dielectric and ferroelectric properties of the PZT with barrier PST deposited at 550 °C were assessed. The dielectric constant and loss factor were estimated as 390 and 0.034 at 100 kHz respectively and the remnant polarisation was 28 µC/cm² at 19 V. The performance of the PZT/PST device structures was compared to similar PZT transducer stacks having widely used barrier TiO₂ layer.