退火温度对Bi3.15(Eu0.7Nd0.15)Ti3O12铁电薄膜力学性能的影响

利用金属有机物分解法(MOD)在Pt/Ti/SiO2/Si(111)衬底上制备了Bi3.15(Eu0.7Nd0.15)Ti3O12(BENT)薄膜,并经600℃、650℃、700℃、750℃退火处理。通过纳米压痕法测试了薄膜的硬度和弹性模量,采用X射线衍射(XRD)测量了薄膜的残余应力。BENT薄膜的晶粒尺寸随着退火温度的升高而不断变大。当晶粒尺寸从37 nm增大到46 nm时,薄膜的硬度值从8.4 GPa减少到3.1 GPa,弹性模量从171.5 GPa减小到141.6 GPa。随着退火温度从600℃升高到750℃时,薄膜的残余压应力值从–743 MPa减小到了–530 MPa。退火温度为600℃的BENT薄膜具有最大的硬度和弹性模量。     

薄膜厚度和溅射功率对有机衬底上ZnO∶Ga薄膜应力的影响

在室温(RT)下,采用直流(DC)磁控溅射在聚碳酸酯(PC)衬底上制备Ga掺杂ZnO(GZO)薄膜。通过X射线衍射(XRD)与基片曲率方法研究薄膜的残余应力。提出并讨论了厚度和溅射功率对GZO薄膜的应力影响并证实所有薄膜的应力均是压缩应力。研究表明随着薄膜厚度的增加,外应力可以得到充分释放。而溅射功率的变化可以改变GZO薄膜的应力和晶粒尺寸。研究表明溅射功率在140W的条件下制备的厚度225nm薄膜具有最大的晶粒尺寸和最小的压缩应力。结果表明改变溅射参数,比如溅射功率和薄膜厚度,GZO薄膜能够有效地释放应力。     

脉冲激光沉积法室温下ZnO薄膜的制备与表征

在室温条件下,采用脉冲激光沉积技术在玻璃衬底上生长了ZnO薄膜.对薄膜的XRD分析表明,ZnO薄膜为六方纤锌矿结构并沿c轴取向生长,且(002)衍射峰的半高峰宽仅为0.24°.薄膜沿c轴方向受到一定的张应力为1.7×108 N/m2.原子力显微镜分析表明薄膜表面较为平整,平均粗糙度约为6.5 nm,晶粒尺寸约为50 nm.此外,透射光谱分析表明薄膜的禁带宽度为3.25 eV,与ZnO体材料的禁带宽度3.30 eV基本相同.     

溶胶-凝胶方法制备BiFeO_3薄膜的微结构和晶粒尺寸效应

使用溶胶凝胶法在Pt/Ti/SiO_2/Si衬底上生长不同厚度与不同稀土掺杂(Nd,Ce,La)的BiFeO_3(BFO)薄膜,高分辨X射线衍射实验结果表明薄膜是由无择优取向的多晶成份组成,不同厚度和掺杂的薄膜都呈现三方相。对比不同厚度BF0薄膜的结构发现,随着薄膜厚度的增加,薄膜的晶粒尺寸呈现增大的趋势,同时晶格常数也随之增大;比较不同掺杂的薄膜,发现随掺杂原子的离子半径增大(Nd,Ce,La),薄膜的晶粒尺寸随之减小,同时薄膜的晶格参数变小。这些结果表明在BFO薄膜中存在晶粒尺寸效应,BFO的晶格随着晶粒尺寸的增大而增大。     

自支撑硼掺杂金刚石膜残余应力和微观应力的XRD分析

利用XRD(包括sin2ψ法)研究了电子辅助热灯丝化学气相沉积法(EA-HFCVD)生长的自支撑硼掺杂多晶金刚石薄膜的残余应力和微观应力.结果表明,薄膜的残余应力为压应力,随着薄膜制备过程中硼流量的增加,应力值有减小的趋势.薄膜的微观应力随着硼流量的增加,由拉应力转变为压应力然后又转变为拉应力.残余应力和微观应力的变化归因于一定量的硼掺杂导致的多晶膜中晶粒尺寸、晶面取向及孪晶变化的共同作用.     

铁电极化诱导的PbTiO3薄膜的取向聚集生长和晶粒尺寸调控

用溶胶凝胶法制备了PbTiO₃薄膜。将含量为0.2%、0.5%和0.8%(摩尔比)的钙钛矿铁电PbTiO₃纳米片加入溶胶体系中,利用纳米片的自发极化调控薄膜的生长。结果表明,纳米片的加入显著影响了薄膜的生长过程和结晶学取向,可制备出(100)高度取向的PbTiO₃薄膜;改变纳米片的浓度,可将薄膜晶粒尺寸由100 nm调控到2 μm。扫描电子显微镜(SEM)、透射电子显微镜(TEM)观测和原位X射线衍射(in-situ XRD)的结果表明,固态薄膜中的晶粒表现出类液相的取向聚集生长特征。其原因可能是,铁电纳米片极化表面的静电力诱导小晶粒的吸附和取向排列,调控了薄膜的(100)取向和晶粒尺寸。     

溅射功率对射频磁控反应溅射制备的Ag2O薄膜微结构的影响

利用射频磁控溅射技术,通过调节溅射功率(P)在200℃、氧氩比为2∶3条件下在玻璃衬底上制备了一系列氧化银(Ag2O)薄膜。利用X射线衍射谱和扫描电子显微镜重点研究了P对Ag2O薄膜微结构的影响。研究结果表明Ag2O薄膜具有(111)择优取向,这可能归结于(111)面的表面自由能最低。随着P从120 W增大到240 W,Ag2O薄膜(111)方向的平均晶粒尺寸从22.92 nm增大到27.96 nm,薄膜的表面结构呈现了从均匀、致密的表面结构向疏松、多孔洞的表面结构的演变。Ag2O(111)衍射峰的2θ角与标准值偏差(2θshift)随P的增大先减小后增大,(111)衍射峰峰位向2θ增大的方向发生了明显的移动。根据量子尺寸效应,薄膜的应力与晶粒尺寸呈反比关系,因此薄膜的应力随P的增大先减小后增大。P=240 W时薄膜的应力最小。从应力的角度,这基本可以合理解释P=210 W时制备的Ag2O薄膜的结晶质量最好,尽管与实验结果有些差异。     

衬底偏压对反应磁控共溅射 Y∶HfO2薄膜电学性能的影响

作为微电子器件中最具发展前景的高介电薄膜材料,HfO₂薄膜得到了学者们的广泛研究。低漏电流是HfO₂薄膜使器件获得优良性能的前提,但易受晶粒尺寸、氧空位和粗糙度等因素影响。针对反应磁控溅射所得薄膜表面粗糙度高及漏电流密度大等缺点,本文在溅射过程中通过在衬底施加偏压的方法降低了HfO₂薄膜的漏电流密度。结果表明：通过在衬底施加适当的偏压使得Y掺杂HfO₂(Y∶HfO₂)薄膜的漏电流密度降低到8×10^-8 A/cm²。漏电流密度的变化与薄膜粗糙度和晶粒尺寸有关,而薄膜粗糙度和晶粒尺寸主要受衬底偏压的影响,但衬底偏压对薄膜物相的影响可以忽略。通过施加衬底偏压,利用反应磁控溅射方法制备了低漏电流和高k值Y∶HfO₂薄膜,可为高性能器件的制备提供基础。     

钒掺杂纳米TiO2薄膜的结构和光吸收性能

采用磁控溅射法制备了不同V含量的纳米TiO₂薄膜,利用SEM、XRD、Raman光谱和UV-vis吸收光谱对V掺杂TiO₂薄膜的表面形貌、结晶特性、晶格应力和光吸收性能进行了分析.结果表明,V掺杂可促进TiO₂薄膜晶粒的定向生长,得到尺寸分布较均匀的哑铃状晶粒,且可抑制薄膜的晶格膨胀和金红石型晶粒的生成.V掺杂TiO₂薄膜处于压应力状态,且应力随V含量增加而增大.V掺杂使导带底向带隙延伸,TiO₂薄膜光学带隙变窄,光响应范围从紫外区红移到可见光区域,提高了薄膜对可见光的吸收率.     

不同晶粒尺寸Mg掺杂(Ba0.6Sr0.4)0.925K0.075TiO3薄膜的直流场介电性能研究

采用溶胶凝胶工艺,在Pt/Ti/SiO2/Si衬底制备了Mg掺杂(Ba0.6Sr0.4)0.925K0.075TiO3(BSKT)薄膜.X射线衍射(XRD)和扫描电镜(SEM)分析测定了物相微结构和薄膜表面形貌,研究了Mg掺杂含量对BSKT晶粒尺寸和直流场介电调谐性能的影响,讨论了直流场介电损耗谱演变的原因.结果表明,Mg掺杂BSKT使薄膜表面粗糙度、晶粒尺寸、介电常量、介电损耗和调谐量都降低;在室温1MHz下,BSKT薄膜有最大的调谐量73.6%;6%(摩尔分数)Mg掺杂BSKT薄膜有最低的介电损耗为0.0088;发现直流场下薄膜的介电损耗谱演变一方面可能与薄膜的晶粒尺寸有关,另一方面也可能与测试温度有关.     

力电多场鼓包法测定PZT铁电薄膜的横向压电系数

为表征Pb(Zr_(0.52)Ti_(0.48))O_3(PZT)薄膜的横向压电性能,以纯力场鼓包测试模型和铁电薄膜材料压电方程为基础,推导了PZT铁电薄膜的力电耦合鼓包本构模型。采用溶胶-凝胶法制备了PZT铁电薄膜,并通过化学腐蚀法获得PZT薄膜鼓包样品。在外加电压为0~14V的条件下进行鼓包测试。结果表明,在纯力场作用下,PZT薄膜的弹性模量和残余应力分别为91.9GPa和36.2MPa;随着电压从2V变化到14V,PZT薄膜的横向压电系数d31从-28.9pm/V变化到-45.8pm/V。本工作所发展的力电耦合鼓包测试技术及力电耦合鼓包本构模型为评价铁电薄膜材料的横向压电性能提供了一种有效的分析方法。     

Stress-induced shifting of the morphotropic phase boundary in sol-gel derived Pb(Zr0.5Ti0.5)O3 thin films

The structure evolution of Pb(Zr_0.5Ti_0.5)O₃ thin films with different thicknesses on the Pt(1 1 1)/Ti/SiO₂/Si substrates has been investigated using X-ray diffraction and Raman scattering. Differing from Pb(Zr_0.5Ti_0.5)O₃ bulk ceramic with a tetragonal phase, our results indicate that for PZT thin films with the same composition monoclinic phase with Cm space group coexisting with tetragonal phase can appear. It is suggested that tensile stress plays a role in shifting the morphotropic phase boundary to titanium-rich region in PZT thin films. The deteriorated ferroelectric properties of PZT thin films can be attributed mainly to the presence of thin non-ferroelectric layer and large tensile stress.     

The effect of LaNiO3 buffer layer thickness on the electric properties of Pb(Zr0.53Ti0.47)O3 thin films deposited on titanium foils

Sol-gel derived Pb(Zr_0.53Ti_0.47)O₃ (PZT) thin films were prepared on LaNiO₃ (LNO) buffered titanium foils. The effect of LNO buffer layer thickness on the electric properties of PZT thin films was investigated. The room temperature dielectric constant of PZT thin films increased with increasing LNO thickness. The remnant polarization of PZT thin films on 150 and 250 nm LNO was about 20 uC/cm². Curie temperatures of PZT thin films were 310, 330 and 340 °C for LNO of 250, 150 and 50 nm respectively. The current-voltage characteristics of PZT thin films were examined for different LNO buffer layer thicknesses, and the space charge limited conduction model was followed in PZT thin films on 50 nm LNO.     

溅射工艺参数对PZT铁电薄膜相变过程的影响

采用射频磁控溅射工艺,在（１１１）Ｐｔ／Ｔｉ／ＳｉＯ２／Ｓｉ衬底上用ＰＺＴ（５３／４７）陶瓷靶制备铁电薄膜。用快速光热退火炉对原位沉积的薄膜进行ＲＴＡ处理。     

电极对PZT铁电薄膜的微观结构和电性能的影响

采用溶胶—凝胶(sol—gel)工艺分别在Pt／Ti／SiO2／Si和LNO／Si电极上制备Pb(Zr0．53，Ti0．47)O3(PZT)铁电薄膜。研究了不同电极材料对PZT铁电薄膜的微结构及电性能的影响。(100)择优取向的PZT／LNO薄膜的介电性能和铁电性能较(111)／(100)取向的PZT／Pt薄膜略有下降，但在抗疲劳特性和漏电流特性方面都有了很大提高。PZT／LNO薄膜10m次极化反转后剩余极化几乎保持未变，直至10^12次反转后，剩余极化仅下降了17％。     

Crystallization behavior and domain structure in textured Pb(Zr0.52Ti0.48)O3 thin films by different annealing processes

Amorphous Pb(Zr_0.52Ti_0.48)O₃ (PZT) thin films were prepared on the Pt/Ti/SiO₂/Si substrates by radio-frequency magnetron sputtering at room temperature. After rapid thermal annealing (RTA) and conventional furnace annealing (CFA) at different temperatures, the films were transformed into polycrystalline PZT thin films with (111) and (100) orientation, respectively. The phase formation and ferroelectric domains correlated with different orientation were systematically investigated by X-ray diffraction and piezoresponse force microscopy. The results showed that the perovskite PZT crystal with [111] orientation hetero-nucleated preferentially on top of the PtPb intermetallic phase at the PZT/Pt interface during RTA process. It is of interest to find that the domain self-organized into a structure with rounded shape at the early stage of crystallization. While the nucleation of the films treated by CFA dominantly homo-nucleated, thus the (100) orientation grains with minimum surface energy were easy to grow. The texture effects on ferroelectric properties of PZT films were also discussed in relation to the domain structure.     

Comparative analysis for the crystalline and ferroelectric properties of Pb(Zr,Ti)O3 thin films deposited on metallic LaNiO3 and Pt electrodes

The crystalline quality and ferroelectricity of the Pb(Zr,Ti)O₃ (PZT) films deposited on the metallic LaNiO₃ (LNO) and Pt electrodes were comparatively analyzed to investigate the possibility for their application to non-volatile memory devices. LNO thin films were successfully deposited on various substrates by using r.f. magnetron sputtering even at a low temperature ranging from 250 to 500 °C, and the ferroelectric PZT thin films were spin-coated onto the LNO and Pt bottom electrodes. Metallic LNO thin films exhibited [100] orientation irrespective of the substrate species and PZT films coated onto LNO films had highly a- and c-axis orientations, while those with Pt bottom electrode were polycrystalline. PZT films with LNO bottom electrode had smaller grain size and larger dielectric constant compared to those grown on the Pt electrode. The ferroelectric thin films fabricated on LNO bottom electrode displayed an asymmetric D–E hysteresis loop, which was explained by the defect effects formed at the interface. Especially, the LNO/PZT/LNO capacitor was found to significantly improve the polarization fatigue and the effects of the LNO electrodes to the fatigue were discussed.     

Drying temperature effects on microstructure, electrical properties and electro-optic coefficients of sol-gel derived PZT thin films

Transparent lead zirconium titanate (PZT) thin film is suitable for a variety of electro-optic application, and the increasing of the electro-optic coefficient of PZT film is one of the important factors for this application. In this study, the main processing variable for improving an electro-optic coefficient was the drying temperature: 300, 350, 450 and 500°C in sol-gel derived PZT thin films. The highest linear electro-optic coefficient (1.65×10⁻¹⁰ (m/V)) was observed in PZT film dried at 450°C. The PZT film showed the highest perovskite content, polarization (P_max=49.58 μC/cm², P_r=24.8 μC/cm²) and dielectric constant (532). A new two-beam polarization (TBP) interferometer with a reflection configuration was used for electro-optic testing of PZT thin films which allows measurement of the linear electro-optic coefficient of thin film with strong Fabry–Perot (FP) effect usually present in PZT thin film.     

锆钛酸铅(PZT)薄膜的自发极化与压电响应

用溶胶－凝胶法在Ｐｔ／Ｔｉ／ＳｉＯ２／Ｓｉ（１００）基片上制备了近等原子比的压电ＰＺＴ薄膜,在准同型相界附近的ＰＺＴ薄膜的应变机制是受极化控制的压电效应,内电场导致薄膜的自发极化定向,使薄膜未经极化就具有明显的压电响应。     

Fabrication of 3-dimensional PbZr(1-x)Ti(x)O3 nanoscale thin film capacitors for high density ferroelectric random access memory devices

PbZr(x)Ti(1-x)O3 (PZT) thin films were deposited on 3-dimensional (3D) nano-scale trench structures for use in giga-bit density ferroelectric random access memories. PZT thin films were deposited by liquid delivery metalorganic chemical vapor deposition using Pb(thd)2, Zr(MMP)4, and Ti(MMP)4 precursors dissolved in ethyl cyclohexane. Iridium thin films were deposited by atomic layer deposition, and they exhibited excellent properties for capacitor electrodes even at a thickness of 20 nm. The trench capacitor was composed of three layers, viz. Ir/PZT/lr (20/60/20 nm), and had a diameter of 250 nm and a height of 400 nm. Almost 100% step coverage was obtained at a deposition temperature of 530 degrees C. The PZT thin film capacitors with a thickness of 60 nm on a planar structure exhibited a remnant polarization (Pr) of 28 microC/cm2, but the Pr value of the 3D PZT capacitors decreased slightly with decreasing 3D trench pattern size. The transmission electron microscope analysis indicated that the PZT thin films had compositional uniformity in the 3D trench region. Both columnar and granular grains were formed on the sidewalls of the trench capacitors, and their relative proportion exhibited strong size dependence. The trench capacitors with more columnar PZT grains showed good switching behavior under an external bias of 2.1 V and had a remnant polarization of 19-24 microC/cm2.