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。     

PZT铁电薄膜结构及疲劳特性研究

铁电薄膜的电疲劳是铁电存储器等应用的主要障碍，我们用Ｓｏｌ－ｇｅｌ（溶胶－凝胶）方法制备ＰＺＴ铁电薄膜，对其结构和疲劳特性的研究表明，组分及工艺因素合影响薄膜的结构，具有玫瑰花形的ＰＺＴ薄膜内部存在较多的带电缺陷，在外电场作用下１０＾６周期后出现疲劳，改进组分配方或改进热处理工艺，使薄膜为纯钙钛矿结构，薄膜的寿命可超过１０＾１１周期。     

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。     

PZT94／6陶瓷热释电性能

采用Ｂｙｅｒ－Ｒｏｕｎｄｙ法，在－１２０℃－＋℃范围内对ＰＺＴ９４／６陶瓷热电性进行了研究。在３５℃左右出现的热释电电流峰是由ＦＲＬ－ＦＲＨ相变引起的。利用此相变特性，可以获得较大的热释电系数，最大可达１２０×１０＾－８Ｃ／ｃｍ＾２．Ｋ 。     

底电极对PLT铁电薄膜结构与电性能的影响

用Ｘ射线衍射和扫描电镜对不同厚度Ｔｉ的Ｐｔ／Ｔｉ电极的物要与形貌进行了分析。用金属有机化合物分解法通过多次匀胶，制备了０．７２－０．８７μｍ厚的ＰＬＴ铁电薄膜。并对其形貌，相结合介电和铁电性能与直流电阻特性进行对比研究，结果表明：不同厚度Ｔｉ的Ｐｔ／Ｔｉ电极对ＰＬＴ铁电薄膜的各种有明显的影响。     

PZT铁电薄膜Sol-Gel技术制备和电性能研究

以乙酸铅(Pb(CH₃COO)₂·3H₂O)、钛酸四丁酯(Ti(OC₄H₉)₄)、硝酸锆(Zr(NO₃)₄·5H₂O)替代锆醇盐为原料,通过在Pt/Ti/SiO₂/si基片与PZT薄膜之间引入PT种子层,采用改进的sol-gel工艺制备出无裂纹,致密性好,晶粒尺寸小且分布均匀的单一钙钛矿结构的Pb(Zr_0.53Ti_0.47)O₃铁电薄膜.实验结果表明,具有PT种子层的PZT铁电薄膜电性能较好.经600℃热处理的具有PT种子层的PZT薄膜,在1kHz测试频率下,其剩余极化强度和矫顽场分别为20μC/cm²和59kV/cm,介电常数和介电损耗分别为385和0.030.     

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Ｓｏ１－Ｇｅｌ法制备的ＰＺＴ铁电陶瓷薄膜的显微结构。发现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好地结晶，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。     

快速热处理对PZT薄膜的微结构及电性能的影响

采用改进的溶胶一凝胶技术,在Ｐｔ／Ｔｉ／ＴｉＯ２／ＳｉＯ２／Ｓｉ（１００）基片上制备了太电ＰＺＴ薄膜,用ＸＲＤ和ＡＦＭ技术分析了不同热处理工艺条件下ＰＺＴ薄膜的微观形貌变化及相结构演化,系统测试了ＰＺＴ薄膜的铁电性能。工艺－结构－性能研究结果表明：快速热处理工艺（ＲＴＡ）有利于ＰＺＴ薄膜保持较低的漏电流密度,热处理温度是影响晶粒大小的主要因素,而保温时间则对ＰＺＴ薄膜的致密性、晶粒均匀度和晶界结合     

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。     

Sol-Gel法制备PZT铁电薄膜新进展

从底电极的选择、过渡层的引入、外延膜的生长、取代阳离子的改性四个方面介绍了Sol-Gel法制备PZT铁电薄膜的研究进展,简述了PZT的Sol-Gel机理研究现状和引起PZT铁电薄膜极化疲劳的原因,分析了Sol-Gel法制备PZT铁电薄膜研究中存在的问题,并提出展望。     

Fabrication of single crystal PZT thin films on glass substrates

 We have successfully transferred heteroepitaxial Pb(Zr,Ti)O₃ (PZT) thin films from MgO substrates on to glass substrates. The transferred PZT thin films exhibit single crystal structure with ferroelectric properties similar to the as-grown epitaxial films. The transferring process comprises coating of Cr-metallized surface of epitaxial PZT thin films, pressing and cementing the Cr-metallized surface on to the glass substrates by silicone rubber, and removing the MgO substrates by chemical etching. This process realizes a fabrication of high-temperature processed PZT thin films onto the glass at room temperature. The process is also available for the transformation of PZT thin films on organic film sheet. The present transfer process reduces the effects of the inevitable strain and/or constraint to rigid substrates for heteroepitaxial growth and has a potential for integration of single crystal piezoelectric PZT devices onto a wide variety of MEMS.     

Influence of irradiation on the switching behavior in PZT thin films

Spatially nonuniform imprint behavior induced by X-ray synchrotron, electron and neutron irradiation has been investigated in sol–gel Pb(Zr,Ti)O₃ thin films. The analysis of the switching current data reveals the strong influence of irradiation on the switching current shape. The obtained effects have been explained as a result of acceleration of the bulk screening process induced by irradiation. It was shown that the spatial distribution of the internal bias field is determined by the domain structure existing during irradiation. The changes in the structural characteristics during fatigue cycling have been reveled by high resolution synchrotron X-ray diffraction experiments on (1 1 1)-oriented PZT-based capacitors with a composition in the morphotropic region. From both ex situ and in situ measurements, microstructural changes with cyclic switching during fatigue have been evidenced and correlated with the evolution of the switching characteristics.     

Improvement of the fatigue and the ferroelectric properties of PZT films through a LSCO seed layer

The ability to optimizate the preparation of Lead Zirconate Titanate (PZT) films on platinized Si substrate by pulsed laser deposition was demonstrated. The effect of the modification of the interface film/electrode through the use of a (La,Sr)CoO₃ (LSCO) seed layer on the remnant polarization, fatigue endurance and stress in PZT films was studied. An improvement on the ferroelectric properties was found with the using of the LSCO layer. A remnant polarization (P_r) of 19.8 μC/cm² and 4.4 μC/cm² for films with and without the LSCO layer were found. In the same way the polarization fatigue decreases significantly after deposition of the LSCO layer between the film and substrate. Atomic force microscopy (AFM) images revealed a different growth process in the films. Current–voltage (I–V) measurements showed that the use of LSCO seed layer improves the leakage current and, on the other hand the conduction mechanisms in the film without LSCO, after the fatigue test, was found to be changed from Schottky to Poole–Frenkel. The trap activation energy (about 0.14 eV) determined from Poole–Frenkel mode agrees well with the energy level of oxygen vacancies. The films stresses were estimated by XRD in order to explain the improvement on the structure and consequentially ferroelectric properties of the films. The model proposed by Dawber and Scott was found to be in agreement with our experimental data, which seems to predict that the oxygen vacancies play an important role on fatigue.     

PZT/ZnO薄膜制备及其结构特性研究

利用固相反应制备的ZnO-Li_(2.2%)陶瓷靶和RF射频磁控溅射技术在Si(100)基片上制备了高度c轴择优取向的ZnO薄膜,XRD和电性能分析表明掺杂Li离子改善了ZnO靶材的结构和性能,同时研究了不同RF溅射温度对ZnO薄膜结构与取向的影响;然后采用sol-gel前驱单体薄膜制备方法,以ZnO为过渡层淀积PZT薄膜,探讨高度c轴(002)择优取向ZnO薄膜对PZT薄膜结构与性能的影响,实验发现在PZT/ZnO异质结构中,致密、均匀和高度c轴择优取向的ZnO可作为晶核,促进PZT钙钛矿结构转化、晶粒(110)择优取向生长,相应降低PZT薄膜的退火温度.     

低温制备Pb(Zr0.52Ti0.48)O3铁电薄膜及其性能研究

采用脉冲激光沉积技术（PLD）在（100）p-Si衬底上,低温淀积、快速退火成功地制备了具有完全钙钛矿结构的多晶PZT铁电薄膜,所制备的PZT铁电薄膜致密、均匀,表现出良好的介电和铁电性能,其介电常数和介电损耗100kHz下分别为320和0.08,剩余极化Pr和矫顽场Ec分别为14μC/cm^2和58kV/cm,＋5V电压下漏电流密度低于10^-7A/cm^2。10^7次极化反转后剩余极化仅下降10％,具有较好的疲劳特性。     

铁电薄膜电疲劳研究进展

铁电薄膜在交变电场下发生电疲劳现象是影响其商业应用的主要障碍，也是目前国内外研究的热点。本文从铁电薄膜电疲劳的影响因素、疲劳机理和消除疲劳的措施出发综述了近年来国内外在铁电薄膜电疲劳研究方面取得的进展。     

改进溶胶-凝胶法制备PZT50/50铁电薄膜

采用改进的溶胶凝胶法在Ｐｔ／Ｔｉ／ＳｉＯ２／Ｓｉ衬底上制备了ＰＺＴ５０／５０铁电薄膜，用Ｘ射线衍射表征了薄膜的物相，用原子力显微镜（ＡＦＭ）表征薄膜的微观形貌，用ＲＴ６６Ａ测量了薄膜的铁电特性，获得了具有优良的铁电性能的晶粒尺寸为１００ｎｍ的ＰＺＴ５０／５０铁电薄膜，在２０Ｖ电压下，Ｐｒ＝３１．８３μＣ／ｃｍ２。     

Microstructure and magnetic properties of zinc ferrite thin films produced by pulsed laser deposition

Zinc ferrite thin films were deposited from a target of zinc ferrite onto a MgO substrate using XeCl excimer laser operating at 308 nm and frequency of 30 Hz. The crystallographic characterizations of the films were performed using X-ray diffraction (XRD). Microstructure, surface morphology, chemical composition and grain size, as well as surface roughness were obtained from scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and atomic force microscopy (AFM). The magnetic properties of the thin films were studied in the temperature range 5–300 K and in fields of up to 5 T using SQUID magnetometry. Data on temperature and field dependence of magnetization provide a strong evidence for superparamagnetism. Paper presented at 8 AGM of MRSI, BARC, Mumbai, 1997.