溅射PZT薄膜的晶体结构和快速热处理

采用常温射频（RF）溅射法和快速热处理相结合的技术，在Pt／Ti／SiO2／Si衬底上，制备出具有铁电性的PZT薄膜。研究了快速热处理工艺条件对PZT薄膜性能的影响。通过X射线衍射法、SEM和AES等方法，分析了PZT薄膜的晶体结构、微结构、薄膜和电极间的界面效应。     

溅射PZT薄膜的晶体结构和快速热处理

采用常温射频（ＲＦ）溅射法和快速热处理相结合的技术，在Ｐｔ／Ｔｉ／ＳｉＯ２／Ｓｉ衬底上，制备出具有铁电性的ＰＺＴ薄膜。研究了快速热处理工艺条件对ＰＺＴ薄膜性能的影响。通过Ｚ射线衍射法、ＳＥＭ和ＡＥＳ等方法，分析了ＰＺＴ薄膜的晶体结构、微结构、薄膜和电极间的界面效应。     

PZT薄膜厚度对BMT/PZT复合薄膜结构及介电性能的影响

采用液相旋涂法制备了Ba(Mg1/3Ta2/3)O3(BMT)/Pb(Zr0.52Ti0.48)O3(PZT)复合薄膜,研究了PZT薄膜厚度对BMT/PZT复合薄膜结构及介电性能的影响。随着PZT薄膜厚度的增加,BMT/PZT复合薄膜的介电常数呈线性增加。当PZT薄膜的厚度较小时,会明显地增加BMT/PZT复合薄膜的介电损耗;当继续增加PZT薄膜的厚度,介电损耗反而下降直到与BMT薄膜的介电损耗值接近。这是由于PZT的介电常数与介电损耗均明显高于BMT薄膜所致,而异质界面的存在抑制了PZT薄膜中畴壁的运动,使其对复合薄膜介电损耗的影响减弱。研究结果表明,PZT薄膜的引入可以提升BMT薄膜的介电常数而对介电损耗的影响不大。     

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％。     

热处理对TaN薄膜微结构及电性能的影响

采用直流磁控溅射制备TaN薄膜,研究了热处理对TaN薄膜微结构及电性能的影响.结果表明,退火温度及退火时间都将影响薄膜的微结构及方阻.随退火温度的升高和时间的延长,TaN薄膜的方阻逐渐增大,但当退火温度高于800℃时,由于氧化严重导致薄膜的方阻异常增大.退火可显著改善薄膜的TCR,制备态TaN薄膜的TCR值为-1.2X10-3,薄膜经800℃退火30min后,其TCR可降低到-7.0x10-4.     

富Pb的PZT铁电薄膜电性能异常

采用金属有机物热分解法制备了不同Ｐｂ过量的锆钛酸铅（ＰＺＴ）铁电薄膜。观测到Ｐｂ过量ＰＺＴ薄膜电滞回线束腰与Ｃ－Ｖ曲线四峰的异常现象,其异常程度随时间回剧。这是薄膜样品有界晶和界面上的ＰｂＯ２相所诱导的陷阱电荷对电畴产生钉扎的结果。陷阱电荷对电畴的钉轧程度与陷阱电荷的密度以及陷阱电荷与电畴的作用状况有关,通过改变晶界处的陷阱电荷的密度与分布可改变薄膜电性能的异常程度。     

Gd掺杂对PZT薄膜介电性能及极化行为的影响

采用sol-gel法在Pt/Ti/SiO₂/Si衬底上制备出高度(100)择优取向的Gd掺杂PZT薄膜(简写为PGZT); 介电测试结果表明, 1mol%Gd掺杂的PZT薄膜介电常数最大, 2mol%Gd掺杂PZT薄膜与未掺杂薄膜的介电常数相差不大, Gd掺入量>2mol%时, 薄膜的介电常数下降; 薄膜的不可逆极化值呈现与介电常数相同的变化趋势, 而可逆极化值变化较小. 在弱电场下(低于矫顽场E_c), 用瑞利定律分析薄膜介电常数随电场强度的变化规律, 1mol%Gd掺杂的薄膜瑞利系数α最大, 说明薄膜中缺陷的浓度最低. 1mol%Gd掺杂的薄膜介电和铁电性能的改善与Gd³⁺在PZT晶格中的占位情况有关.     

Cu—TiN复合薄膜的微结构与电性能

本文采用ＳＥＭ,ＥＤＡＸ和ＴＥＭ等手段研究了多靶磁控溅射制备的Ｃｕ－ＴｉＮ复合薄膜,并测定了薄膜的电阻率。研究表明,复全薄膜的微结构随ＴｉＮ含量及其片高温发生明显变化,其电阻率在基片温度约为２００℃时取得极不值,约为室温沉积薄膜电位率的１／４。     

快速热处理对BaSrTiO3薄膜微结构的影响

采用射频溅射法在Si基片上制备BaSrTiO3(BST)薄膜,利用X射线衍射和原子力显微镜(AFM)研究了快速热处理温度和时间对BaSrTiO3薄膜微结构的影响.结果表明:BST薄膜的衍射峰强度和结晶度随退火温度的升高而提高.随退火温度的升高,BST薄膜的表面粗糙度经历先降低后增大的过程,而BST薄膜的晶粒尺寸单调减小.当退火温度为700℃时,随退火时间的增加,BST薄膜的晶粒尺寸几乎不发生变化,而表面粗糙度单调减小.     

衬底对PZT铁电薄膜显微结构的影响

利用ＸＲＤ和ＳＥＭ观察了在不同衬底材料上用Ｓｏｌ－Ｇｅｌ法制备的ＰＺＴ铁电陶瓷薄膜的显微结构，发ＰＺＴ薄膜的结晶性能受衬底材料的影响极大。ＰＺＴ薄膜在金属铂片上能够很结晶。而在单晶硅片上则很难结晶，其在镀铂硅片上的结晶难易程度介于金属铂片与单晶硅片之间，在衬底上制备ＰＴ过渡层可以促进ＰＺＴ薄膜的结晶。     

Ferroelectricity and Antiferroelectricity of Doped Thin HfO2‐Based Films

The recent progress in ferroelectricity and antiferroelectricity in HfO₂‐based thin films is reported. Most ferroelectric thin film research focuses on perovskite structure materials, such as Pb(Zr,Ti)O₃, BaTiO₃, and SrBi₂Ta₂O₉, which are considered to be feasible candidate materials for non‐volatile semiconductor memory devices. However, these conventional ferroelectrics suffer from various problems including poor Si‐compatibility, environmental issues related to Pb, large physical thickness, low resistance to hydrogen, and small bandgap. In 2011, ferroelectricity in Si‐doped HfO₂ thin films was first reported. Various dopants, such as Si, Zr, Al, Y, Gd, Sr, and La can induce ferro­electricity or antiferroelectricity in thin HfO₂ films. They have large remanent polarization of up to 45 μC cm^?2, and their coercive field (≈1–2 MV cm^?1) is larger than conventional ferroelectric films by approximately one order of magnitude. Furthermore, they can be extremely thin (<10 nm) and have a large bandgap (>5 eV). These differences are believed to overcome the barriers of conventional ferroelectrics in memory applications, including ferroelectric field‐effect‐transistors and three‐dimensional capacitors. Moreover, the coupling of electric and thermal properties of the antiferroelectric thin films is expected to be useful for various applications, including energy harvesting/storage, solid‐state‐cooling, and infrared sensors.     

Effects of Heat Treatment on the Microstructure and Optical Properties of Sputtered GeO2 Thin Films

Microstructure and composition significantly influence the physical properties of thin films. Therefore, these can be adapted to enhance the functionality of thin films for practical applications. Herein, the anomalous microstructural evolution of sputtered GeO₂ thin films based on postdepositional heat treatments is reported. Temperature-dependent microstructural variations are investigated systematically via a combinatorial postdepositional heat treatment employing a natural thermal gradient in a tube furnace. Heat treatment under an oxidizing atmosphere results in a transition from the amorphous phase to the quartz phase, and subsequent heat treatments under a reducing atmosphere cause H₂O-incorporated chemical reactions. Hence, these conditions create unique microstructural features and yield optical transmittance variations in the GeO₂ thin films. The phase transition induces the formation of spherulitic hexagonal GeO₂ crystallites, and further increase in the temperature promotes the agglomeration of crystallites in the amorphous matrix. The incorporation of H₂O results in the growth of the microstructure, and the chemical reduction to Ge metal begins to generate small granules from the boundary of the microstructures. The experimental results and proposed mechanisms presented herein for the microstructural and compositional changes serve as references for designing the physical properties of thin films.     

Atomic Origins of Enhanced Ferroelectricity in Nanocolumnar PbTiO3/PbO Composite Thin Films

Nanocomposite films hold great promise for multifunctional devices by integrating different functionalities within a single film. The microstructure of the precipitate/secondary phase is an essential element in designing composites’ properties. The interphase strain between the matrix and secondary phase is responsible for strain-mediated functionalities, such as magnetoelectric coupling and ferroelectricity. However, a quantitative microstructure-dependent interphase strain characterization has been scarcely studied. Here, it is demonstrated that the PbTiO₃(PTO)/PbO composite system can be prepared in nano-spherical and nanocolumnar configurations by tuning the misfit strain, confirmed by a three-dimensional reconstructive microscopy technique. With the atomic resolution quantitative microscopy with a depth resolution of a few nanometers, it is discovered that the strained region in PTO is much larger and more uniform in nanocolumnar compared to nano-spherical composites, resulting in much enhanced ferroelectric properties. The interphase strain between PbO and PTO in the nanocolumnar structure leads to a giant c/a ratio of 1.20 (bulk value of 1.06), accompanied by a Ti polarization displacement of 0.48 Å and an effective ferroelectric polarization of 241.7 µC cm⁻², three times compared to the bulk value. The quantitative atomic-scale strain and polarization analysis on the interphase strain provides an important guideline for designing ferroelectric nanocomposites.     

采用Sol-gel法制备梯度复合热释电薄膜

以TaCl5和NbCl5为原料制备了乙醇钽和乙醇铌,对溶胶-凝胶法制备KTa1-xNbxO3薄膜的工艺过程、影响因素进行了研究,提出了优化的制备工艺,采用溶胶-凝胶法在Pt/Ti/SiO2/Si衬底上制备了组分梯度复合KTa1-xNbxO3热释电薄膜.     

不同晶化处理方式对PZT薄膜性能的影响

采用改进的溶胶一凝胶（sol—gel）法在Pt／Ti／SiO2／Si基片上制备PZT薄膜,研究不同的晶化处理方式对PZT薄膜的微观结构、表面形貌及电学性能的影响。实验结果表明：快速晶化处理方式更有利于薄膜沿（110）方向的择优生长;并且相对于常规晶化处理方式,快速晶化处理方式制备的PZT薄膜晶粒均匀,排布有序,可有效的提高薄膜的表面质量。电学性能测试结果表明,这种表面形貌可以有效地降低漏电流。     

水热处理对ZnO薄膜微结构及光学性能的影响

基于溶液工艺和水热处理制备了ZnO薄膜。采用椭圆偏振光谱分析仪,原子力显微镜,X射线衍射仪研究和分析了水热处理温度对薄膜的微观形貌,光学特性,晶体结构的影响。实验结果表明,水热处理温度由110℃升高到130℃,薄膜光学带隙由3.19eV增大到3.31eV,而薄膜表面粗糙度从19.3nm降到12.9nm。然而,当处理温度超过140℃后,与130℃下处理的膜相比质量显著劣化。此外,130℃下水热处理的膜与500℃下高温退火的膜对比表明水热法有相似的光学特性,同时,XRD分析表明水热处理能改善晶体特性。证明了利用水热处理能够极大地降低溶液法制备ZnO薄膜所需的退火温度。     

Microstructure and Magnetic Properties of Electrodeposited Fe-Based Thin Films on Silicon Substrate Under Heat Treatment

Three kinds of Fe-based thin films, Fe–20%Ni–80%, Fe–60%Co–40%, and Fe–10%Ni–60%Co–30% (at %), were prepared on silicon (1 1 1) substrates by direct current electrodeposition with the optimized plating conditions. Films were annealed at various temperatures from 200 to 400 °C, varying time from 2 to 4 h. The microstructure, surface morphology, and chemical composition have been investigated by X-ray diffraction, scanning electron microscopy, energy dispersive spectrometer with electron probe micro-analysis, respectively. The magnetic properties were measured by the superconducting quantum interference device magnetometer. Effect of heat treatment on films is then discussed.     

溶胶—凝胶法制备（Pb,La）TiO3铁电陶瓷薄膜的研究

用红外光谱研究了溶胶－凝胶法制备ＰＬＴ铁电陶瓷薄膜的成胶机理，研究了前体溶液的稳定性及多次覆膜工艺。     

Understanding the Role of Ferroelastic Domains on the Pyroelectric and Electrocaloric Effects in Ferroelectric Thin Films

Temperature‐ and electric‐field‐induced structural transitions in a polydomain ferroelectric can have profound effects on its electrothermal susceptibilities. Here, the role of such ferroelastic domains on the pyroelectric and electrocaloric response is experimentally investigated in thin films of the tetragonal ferroelectric PbZr_0.2Ti_0.8O₃. By utilizing epitaxial strain, a rich set of ferroelastic polydomain states spanning a broad thermodynamic phase space are stabilized. Using temperature‐dependent scanning‐probe microscopy, X‐ray diffraction, and high‐frequency phase‐sensitive pyroelectric measurements, the propensity of domains to reconfigure under a temperature perturbation is quantitatively studied. In turn, the “extrinsic” contributions to pyroelectricity exclusively due to changes between the ferroelastic domain population is elucidated as a function of epitaxial strain. Further, using highly sensitive thin‐film resistive thermometry, direct electrocaloric temperature changes are measured on these polydomain thin films for the first time. The results demonstrate that temperature‐ and electric‐field‐driven domain interconversion under compressive strain diminish both the pyroelectric and the electrocaloric effects, while both these susceptibilities are enhanced due to the exact‐opposite effect from the extrinsic contributions under tensile strain.