不同衬底上Pb(Zr0.52Ti0.48)O3择优取向铁电薄膜的制备和研究

通过MOD法在Si(100)和Pt(111)/Ti/SiO₂/Si基片上制备出LaNiO₃ ( LNO)薄膜.再通过修 正的Sol-gel法，在Pt(111)/Ti/SiO₂/Si,LNO/Si(100)和LNO/Pt/Ti/SiO_{2< /sub>/Si三种衬底上 制备出具有择优取向的Pb(Zr0.52Ti0.48)O3铁电薄膜. 经XRD分析表明，L NO薄膜具有(100)择优取向的类钙钛矿结构；PZT薄膜均具有钙钛矿结构，且在Pt(111)/Ti/S iO2/Si衬底上的薄膜以(110)择优取向，在LNO/Pt/Ti/SiO2/Si和LN O/Si(100)衬底上的 薄膜以(100)择优取向.经场发射SEM分析和介电、铁电性能测试表明，在LNO/Si和LNO/Pt/Ti /SiO2/Si衬底上的PZT薄膜的平均粒径、介电常数以及剩余极化强度均比以Pt/T i/SiO2/Si为衬底的薄膜大. 关键词： 3}薄膜')" href="#">LaNiO₃薄膜 PZT铁电薄膜 择优取向 剩余极化强度     

(111)择优取向的Pb(Zr0.52Ti0.48)O3铁电薄膜的制备及研究

选用不同浓度的Pb(Zr0.52Ti0.48)O3溶胶,用Sol-gel法在Pt/Ti/SiO2/Si基片上沉积一层厚度不同的Pb(Zr0.52Ti0.48)O3(PZT52)过渡层,经400℃烘烤、550℃退火等程序后,再用Sol-gel法在PZT52过渡层上沉积Pb(Zr0.52Ti0.48)O3薄膜.XRD分析表明,有PZT52过渡层的Pb(Zr0.52Ti0.48)O3薄膜具有(111)择优取向的钙钛矿结构,且随着过渡层厚度的增加,Pb(Zr0.52Ti0.48)O3薄膜的(111)择优取向程度越高.SEM分析表明,当PZT52过渡层的厚度达到14nm以上,Pb(Zr0.52Ti0.48)O3薄膜结晶程度得到明显改善,平均晶粒尺寸大大增加.介电、铁电性能测试表明,与没有过渡层的Pb(Zr0.52Ti0.48)O3薄膜相比,有PZT52过渡层的Pb(Zr0.52Ti0.48)O3薄膜具有较大的介电常数和剩余极化强度,而介电损耗则较小.     

不同衬底上Pb(Zr0.52Ti0.48)O3择优取向铁电薄膜的制备和研究

通过MOD法在Si(100)和Pt(111)/Ti/SiO2/Si基片上制备出LaNiO3 (LNO)薄膜.再通过修正的Sol-gel法,在Pt(111)/Ti/SiO2/Si,LNO/Si(100)和LNO/Pt/Ti/SiO2/Si三种衬底上制备出具有择优取向的Pb(Zr0.52Ti0.48)O3铁电薄膜.经XRD分析表明,LNO薄膜具有(100)择优取向的类钙钛矿结构;PZT薄膜均具有钙钛矿结构,且在Pt(111)/Ti/SiO2/Si衬底上的薄膜以(110)择优取向,在LNO/Pt/Ti/SiO2/Si和LNO/Si(100)衬底上的薄膜以(100)择优取向.经场发射SEM分析和介电、铁电性能测试表明,在LNO/Si和LNO/Pt/Ti/SiO2/Si衬底上的PZT薄膜的平均粒径、介电常数以及剩余极化强度均比以Pt/Ti/SiO2/Si为衬底的薄膜大.     

Pb(Zr0.3Ti0.7)O3铁电薄膜激光感生电压效应

采用脉冲激光沉积(PLD)技术在LaSrAlTaO₃(LSATO),LaAlO₃(LAO)和SrTiO₃(STO)的单晶倾斜衬底上成功制备了Pb(Zr_0.3Ti_0.7)O₃(PZT)薄膜,在三种倾斜衬底上生长的PZT薄膜中都首次发现了LIV效应.对PZT/LSATO薄膜在a,c轴两种不同取向择优生长下的LIV效应做了研究,发现在薄膜c轴取向择优生长 关键词： 激光感生电压效应 铁电薄膜 薄膜生长取向 原子层热电堆     

重温Pb(ZrxTi1-x)O3铁电薄膜极化疲劳问题

具有ABO3型钙钛矿结构的Pb(ZrxTi1-x)O3 (PZT)展示出良好的铁电极化性能,是使用最广的铁电材料.然而,在将它应用于铁电存储时,PZT薄膜遭遇到极化疲劳问题而被SrBi2Ta2O9 (SBT)等铁电体所替代,这一问题至今未能得到妥善解决.文章首先通过变温极化疲劳实验充分理解PZT极化疲劳的基本过程,然后有针对性地进行材料设计,获得基本无极化疲劳的PZT铁电薄膜.     

多孔未极化Pb(Zr0.95Ti0.05)O3铁电陶瓷单轴压缩力学响应与相变

通过添加造孔剂的方法制备了四种不同孔隙率未极化PZT95/5铁电陶瓷. 采用非接触式的数字散斑相关性分析(digital image correltation, DIC)全场应变光学测量技术, 对多孔未极化PZT95/5 铁电陶瓷开展了单轴压缩实验研究, 讨论了孔隙率对未极化PZT95/5铁电陶瓷的力学响应与畴变、相变行为的影响. 多孔未极化PZT95/5铁电陶瓷的单轴压缩应力-应变关系呈现出类似于泡沫或蜂窝材料的三阶段变形特征, 其变形机理主要归因于畴变和相变的共同作用, 与微孔洞塌缩过程无关. 多孔未极化PZT95/5铁电陶瓷的弹性模量、压缩强度都随着孔隙率的增加而明显降低, 而孔隙率对断裂应变的影响较小. 预制的微孔洞没有改善未极化PZT95/5铁电陶瓷材料的韧性, 这是因为单轴压缩下未极化PZT95/5铁电陶瓷的断裂机理是轴向劈裂破坏, 微孔洞对劈裂裂纹传播没有起到阻碍和分叉作用. 准静态单轴压缩下多孔未极化PZT95/5铁电陶瓷畴变和相变开始的临界应力都随着孔隙率的增大而呈线性衰减, 但相变开始的临界体积应变却不依赖孔隙率.     

La0.3Sr0.7TiO3模板层对Pb(Zr0.5Ti0.5)O3薄膜的铁电性能增强效应的研究

通过sol-gel法在Si (111) 基片上分别制备了LaNiO₃(LNO)底电极和LaNiO₃/La_0.3Sr_0.7TiO₃ (LNO/LSTO)底电极.然后采用sol-gel 方法，在两种衬底上分别制备了Pb (Zr_0.5Ti_0.5)O₃ (PZT)铁电薄膜.XRD分析表明，两种PZT薄膜均具有钙钛矿结构，且在LNO底电极上的PZT薄膜呈(100) 择优取向，而在LNO/LSTO底电极上的PZT薄膜呈随机取向.铁电性能测试表明，相对LNO衬底上制备的PZT薄膜，在LNO/LSTO底电极上制备的PZT薄膜的剩余极化强度得到了有效的增强，同时矫顽场也增大.介电常数和漏电流的测试表明，LNO/LSTO底电极上制备的PZT薄膜具有大的介电常数和漏电流. 关键词： PZT薄膜 铁电性 漏电流 0.3Sr_0.7TiO₃')" href="#">La_0.3Sr_0.7TiO₃     

Pb(Zr0.52Ti0.48)O3陶瓷畴界粘滞运动的介电损耗模拟

对不同频率下(1—10kHz)Pb(Zr_0.52Ti_0.48)O₃多晶陶瓷的介电性能的测量表明：在接近铁电相变温度T_c以下存在一介电损耗峰,该峰具有弛豫特征但不满足Arrhenius关系．这一损耗峰被认为是由于畴界与晶格、缺陷钉扎的互作用引起的．用畴界粘滞运动的动力学方程,考虑陶瓷样品中T_c离散分布的情况,模拟了该介电损耗峰在不同频率下的行为,得到了与实验数据一致的结果．并由拟合参数计算了畴界运动     

外延PbZr0.4Ti0.6O3薄膜厚度对其铁电性能的影响

从Landau-Devonshire唯象理论出发，考虑到晶格失配导致的NFDA3位错应力场与极化场的耦合，研究了在SrTiO₃衬底上外延生长的PbZr_0.4Ti_0.6O₃薄膜厚度对其自发极化强度、电滞回线的影响. 结果表明，产生刃位错的PbZr_0.4Ti_0.6O₃薄膜临界厚度为～1.27nm，当薄膜厚度大于临界厚度时，在所形成的位错附近，极化强度出现急剧变化，形成自发极化强度明显减弱的“死层”；随着薄膜厚度的减小，位错间距增大，“死层”厚度与薄膜总厚度之比增加. 由薄膜电滞回线的变化情况可知，其剩余极化强度随着薄膜厚度的减小而逐渐减小. 关键词： 铁电薄膜 自发极化强度 电滞回线 位错     

含铜铁电电容器SrRuO3/Pb(Zr0.4Ti0.6)O3/SrRuO3/Ni-Al/Cu/Ni-Al/SiO2/Si异质结的研究

应用磁控溅射法以Ni-Al同时作为Cu与SiO₂/Si,Cu与SRO薄膜之间的阻挡层材料,将Cu与SiO₂/Si衬底和氧化物薄膜电极隔离,避免它们在高温氧气氛中发生化学反应和互扩散,实现了Cu薄膜与氧化物铁电电容器的集成.采用X射线衍射仪(XRD)和原子力显微镜(AFM)研究了不同温度下快速退火的SrRuO₃(SRO)/Ni-Al/Cu/Ni-Al/SiO₂/Si含Cu异质结的微结构和表面形貌,结果发现SRO/Ni-Al/Cu/Ni-Al/SiO₂/Si含Cu多层异质结薄膜在高达750 ℃仍然具有较强的Cu衍射峰和比较平整的表面,显示出了很好的高温热稳定性.研究了"室温长高温退"和"低温长高温退"两种工艺手段,发现在制备含Cu多层氧化物薄膜异质结时,低温长高温后退火的方式要优于常规的室温长高温后退火方式,通过低温长高温退工艺可以缓解应力、削弱界面粗化和避免高温生长对阻挡层和Cu薄膜结构的破坏.最后结合sol-gel法将Pb(Zr_0.4Ti_0.6)O₃(PZT)生长在该含Cu异质结上,制备得SRO/PZT/SRO/Ni-Al/Cu/Ni-Al/SiO₂/Si含Cu铁电电容器,研究了电容器的薄膜结构、铁电性能和漏电特性等,发现制备的含Cu铁电电容器具有很好的铁电性能,如电滞回线趋势饱和,剩余极化强度高达~42 μC/cm²,矫顽电压为~1.0 V,介电常数~1600,漏电流~1.83×10^-4 A/cm²,以及良好的抗疲劳特性和保持特性等,表明导电性优良的Cu薄膜可以应用于高密度高性能铁电电容器.对其漏电机理研究表明,SRO/PZT/SRO含Cu铁电电容器满足空间电荷限制传导机理. 关键词： Cu PZT 铁电电容器 Ni-Al     

Phase compositions and ferroelectric properties of Pb(Zr0.52,Ti0.48)O3 thin films with different highly orientations prepared by a sol-gel route

It is shown that different highly oriented Pb(Zr_0.52,Ti_0.48)O₃ films can be obtained on Pt/Ti/SiO₂/Si substrate using a sol-gel technique. The effects of pyrolysis temperature on the orientation, phase composition and ferroelectric properties of the films are investigated. It is found the ferroelectric hysteresis loops of (1 1 1)-oriented film, (1 1 1) and (1 0 0) mix-oriented film can both be saturated when the external electric field is large enough, whereas the hysteresis loop of (1 0 0)-oriented film is difficult to saturate. The analysis of X-ray diffraction indicated the possibility of different phase composition in different oriented films under large film residual stress. Higher remnant polarization (53 μC/cm²) for (1 0 0)-oriented film can be attributed to its more tetragonal phase composition, which results in that the in-plane domain switching can continuously occur with external electric field increasing.     

A comparative study of fibre-textured and epitaxial Nb-doped Pb(Zr0.53Ti0.47)O3 thin films on different substrates

Fibre-textured and epitaxial Nb-doped Pb(Zr_0.53Ti_0.47)O₃ (PNZT) thin films were grown on the different substrates by a sol-gel process. The [1 0 0]- and [1 1 1]-fibre-textured polycrystalline PNZT films were obtained on platinized silicon substrates by introducing PbO and TiO₂ seeding layers, while the [0 0 1]- and [1 1 1]-oriented epitaxial PNZT films were formed directly on Nb-doped SrTiO₃ (Nb:STO) single-crystal substrates with (1 0 0) and (1 1 1) surfaces, respectively. The preferential orientation and phase structure of the fibre-textured and epitaxial PNZT films, as well as their influences on the electrical properties were investigated. Higher remnant polarization (P_r) and piezoelectric coefficient (d₃₃) were obtained for the epitaxial PNZT films on Nb:STO substrates than that for the fibre-textured ones on platinized silicon substrates. For both fibre-textured and epitaxial cases, the PNZT films with [1 0 0]/[0 0 1] orientations show higher piezoelectric responses than [1 1 1]-oriented ones, whereas better ferroelectric properties can be obtained in the latter. The intrinsic and extrinsic contributions were discussed to explain the difference in electrical properties for differently oriented fibre-textured and epitaxial PNZT films on different substrates.     

Fabrication of the hydrogen resistive ferroelectric film of the (Pb0.72La0.28)Ti0.93O3/Pb(Zr0.52Ti0.48)O3/(Pb0.72La0.28)Ti0.93O3 heterostructure by a pulsed laser deposition method

(Pb_0.72La_0.28)Ti_0.93O₃ (PLT)/Pb(Zr_0.52Ti_0.48)O₃ (PZT)/PLT heterostructure was fabricated by using a pulsed laser deposition method. After depositing this structure, the hydrogen annealing process was performed in the forming gas (95% N₂ + 5% H₂) at a substrate temperature of 400 °C for 30 min to study the effects of hydrogen passivation.The heterostructure was not degraded by the hydrogen annealing in contrast with the case of PZT film without buffer layers. This heterostructure showed almost no degradation in terms of the remanent polarization even after the H₂ annealing, while the PZT film exhibited 64% reduction, which is from 20.1 to 7.3 μC/cm² after the annealing. The leakage current was decreased by an order in the case of the heterostructure, while the leakage current of the PZT film increased by an order.These can be explained that the PLT bottom buffer layer works as a seeing layer to help the PZT growth and the top PLT buffer layer acts as a barrier for penetrating hydrogen atoms.     

Investigation on FR(LT)–FR(HT) phase transition and pyroelectric properties of pulsed laser deposited Pb(Zr0.93Ti0.07)O3 thin films

The preparation process, crystallinity and electrical properties of pulse laser deposited Pb(Zr_xTi_1−x)O₃ (PZT) thin films were investigated in this paper. PZT (x = 0.93) thin film samples deposited at different substrate temperatures were prepared. Si (1 1 0) was the substrate; Ag and YBCO were the top electrode and the bottom electrode respectively. The bottom electrode YBCO was deposited on the Si substrate by pulsed laser deposition (PLD), and then PZT was epitaxially deposited on YBCO also by PLD. After annealing, the top electrode Ag was prepared on PZT by thermal evaporation, and then the Ag/PZT/YBCO/Si structured thin films were obtained. The XRD and the analysis of their electrical characters showed that, when the substrate temperature was elevated from 600 °C to 800 °C, the crystallinity and electrical properties of PZT thin films became better and better, and the F_R(LT)–F_R(HT) phase transition of PZT (x = 0.93) thin films occurred at 62 °C. The PZT film deposited at 800 °C had the best pyroelectric properties, and when the F_R(LT)–F_R(HT) phase transition of this film occurred, the peak value of pyroelectric coefficient (p) was obtained, with a value of 1.96 × 10⁻⁶ C/(cm² K). The PZT film deposited at 800 °C had the highest remnant polarization (P_r) and the lowest coercive field (E_c), with the values of 34.3 μC/cm² and 41.7 kV/cm respectively.     

Infrared optical properties of Ba(Zr0.20Ti0.80)O3 and Ba(Zr0.30Ti0.70)O3 thin films prepared by sol-gel method

Ba(Zr_xTi_1−x)O₃ (BZT) (x = 0.20 and 0.30) thin films are deposited on Pt(1 1 1)/Ti/SiO₂/Si(1 0 0) substrate by sol-gel method. X-ray diffraction patterns show that the thin films have a good crystallinity. Optical properties of the films in the wavelength range of 2.5-12 μm are studied by infrared spectroscopic ellipsometry (IRSE). The optical constants of the BZT thin films are determined by fitting the IRSE data using a classical dispersion formula. As the wavelength increases, the refractive index decreases, while the extinction coefficients increase. The effective static ionic charges are derived, which are smaller than that in a purely ionic material for the BZT thin films.     

Nanoembossing and piezoelectricity of ferroelectric Pb(Zr0.3,Ti0.7)O3 nanowire arrays

Arrays of ferroelectric PZT nanowires with lateral size down to 200 nm were fabricated by nanoembossing technology. Structural characterization of the embossed PZT film was studied by Raman spectroscopy. Multidomain configurations of a single nanowire have been explored by vertical mode piezoresponse force microscopy (VPFM). The local electric polarization of the individual ferroelectric nanowire has also been investigated. Excellent ferroelectric and piezoelectric characteristics observed in the embossed PZT nanowires suggest nanoembossing technique proposed in this work is promising to become a useful method for ferroelectric nanowires fabrication.     

PbTiO3/PbZr0.3Ti0.7O3/PbTiO3夹心结构铁电薄膜子晶层的优化

用Sol-Gel法制备了Pb_(1+x)TiO₃/PbZr_03Ti_07O₃/Pb_(1+x)TiO₃(PT/PZT/PT)夹心结构及PZT铁电薄膜,为了获得高质量的PT/PZT/PT夹心结构铁电薄膜,使用不同过量Pb配比(x)的PbTiO₃ (PT)层进行制备,以获得优化的PT子晶层.X射线 关键词： PT/PZT/PT 夹心结构 子晶 铁电薄膜     

PbTiO3/PbZr0.3Ti0.7O3/PbTiO3夹心结构铁电薄膜子晶层的优化

用Sol-Gel法制备了Pb_(1+x)TiO₃/PbZr_03Ti_07O₃/Pb_(1+x)TiO₃(PT/PZT/PT)夹心结构及PZT铁电薄膜，为了获得高质量的PT/PZT/PT夹心结构铁电薄膜，使用不同过量Pb配比(x)的PbTiO₃ (PT)层进行制备，以获得优化的PT子晶层.X射线