非晶YBCO薄膜热释电红外探测器

介绍了非晶YBCO薄膜用作非制冷热释电红外探测器材料。它在室温下显示出强的热释电行为,并且容易在室温下采用射频磁控溅射法沉积,制备工艺与CMOS工艺相兼容,是 一种很有潜力的热释电探测器材料。并介绍了非晶YBCO热释电薄膜的研究现状,阐述了该薄膜及其探测器的制备技术和研究动向。     

低氟溶胶-凝胶法制备的YBa2Cu3O7-δ薄膜的生长取向和超导性能研究

本文采用低氟溶胶-凝胶法在(001)取向LaAlO3(LAO)的单晶衬底上制备了YBa2Cu3O7-δ (YBCO)薄膜。利用X-射线衍射仪(XRD)、扫描电子显微镜(SEM)和高分辨透射电子显微镜(HRTEM)对薄膜的微观结构进行了表征分析,并用标准四探针技术对薄膜进行了超导电性能测试。实验结果表明,在湿度足够大的热处理气氛中制备的YBCO薄膜较在湿度相对较小的处理气氛中制备的薄膜具有更好的c轴生长织构和超导性能。根据经典的形核理论、化学反应热力学原理并结合所得到的实验结果,我们解释了在一定湿度条件下YBCO薄膜的结晶和生长机制。研究表明残留在YBCO薄膜中的第二相会引起晶格畸变,进而诱发a轴取向YBCO晶粒的形成,且热处理气氛中水蒸汽的含量对制备具有c轴取向且超导性能较好的YBCO薄膜有十分重要的作用。     

低氟溶胶-凝胶法制备的YBa2Cu3O7-δ薄膜的高分辨电子显微镜研究

本文采用一种新的低氟溶胶-凝胶法在LaAlO3(LAO)单晶衬底上制备出表面质量良好的YBa2Cu3O7-δ(YBCO)薄膜,薄膜厚度约为280 nm.与传统的all-TFA法相比,减少了大约60%的HF气体的释放量并大大缩短了热处理周期.通过控制退火过程中气氛的湿度减少了薄膜中a轴晶粒的体积分数并提高了临界电流密度Jc.在高分辨透射电子显微镜(HRTEM)下获得了薄膜的高分辨图像及电子衍射花样.从高分辨像可以看出,薄膜的生长从衬底开始沿c轴方向形成明显的层状结构,仅在薄膜的自由表面50 nm范围内有少许与c轴成90 °的a轴晶粒.进一步通过傅立叶变换滤波获得了薄膜与衬底界面的清晰原子像,发现YBCO薄膜与LAO衬底之间保持了很好的共格和外延生长关系,薄膜与衬底之间没有任何非晶过渡层.     

非晶衬底上择优取向ZnO纳米晶薄膜的溶胶-凝胶法制备技术

使用一种新的溶胶-凝胶技术制备了ZnO固体薄膜,此技术的特点在于操作简单、环保、实用.此技术可在非晶基片(如玻璃、石英等)上制备c轴择优取向的大面积ZnO纳米晶薄膜.薄膜的红外透过率高,具备制作无机红外-紫外双色探测器的紫外光敏材料和光伏有机太阳能电池、有机红外探测器的透明导电电极等光电子器件的材料应用价值.     

溶胶-凝胶法制备PZT薄膜研究进展

随着微机电系统(MEMS)产业的快速发展,铁电薄膜材料作为微机电器件的重要组成部分而愈受重视。锆钛酸铅(PZT)薄膜具有优越的压电性、热释电性及光电性等性能,在微电子、压电、光学及半导体等领域展现了巨大的应用潜力。因此,高性能PZT薄膜的制备技术及制备工艺一直备受关注。其中,溶胶凝胶法因具有易于控制成分,所需设备成本低及制备薄膜的均匀性好等优点而被广泛用于PZT薄膜制作中。该文在溶胶凝胶法基本原理及制作工艺的基础上,着重分析了溶胶凝胶法制备PZT薄膜的研究现状,总结了当前溶胶凝胶法的技术特点,并指出了研究中存在的不足及未来的潜在改进方向。     

化合物半导体

0207926VO_2薄膜及电学开关特性[刊]/邱家稳//真空科学与技术学报.—2001,21(6).—485～488.477(K)用溶胶,凝胶法在非晶玻璃上制备 VO_2薄膜,经过熔融、涂膜、烘干和热处理等工艺最后得到电阻相变2～3个量级的 VO_2薄膜。对烘干温度、熔融温度、膜厚和热处理温度对薄膜电阻开关特性的影响进行了研     

复合热释电薄膜红外探测器的研究

热绝缘结构是热释电红外探测器的关键技术之一."复合热释电薄膜红外探测器"是用多孔SiO2薄膜来绝热的,这种无空气隙的新型结构被认为具有更高的机械强度和可靠性.采用溶胶-凝胶技术制备了热导率极低的多孔SiO2薄膜,用金属有机物热分解法制备了优质的铁电薄膜,实现了"复合热释电薄膜"热绝缘结构,获得的星探测率最大值达9.3×107cm.Hz1/2/W.通过快速热处理工艺的采用,提高薄膜一次成膜厚度的研究,改善了薄膜制备与微电路工艺的兼容性.研究了多孔膜厚度、孔径分布与探测率的关系,探讨了镍酸镧(LNO)薄膜作为缓冲层、红外吸收层和上电极的多功能作用.结果表明:孔径分布小的多孔膜有利于探测器性能的提高.在此结构中,存在热性能和电性能的折中问题,多孔膜厚度有一个临界值.LNO薄膜的引入,可以改善性能、简化结构和工艺.讨论了低温铁电薄膜的制备和性能,以及与微电路实现单片集成等问题.     

高温超导薄膜在激光辅助化学刻蚀中的表面特性

提出了将激光辅助化学刻蚀技术应用于钇钡铜氧(YBCO)高温超导薄膜的刻蚀,研究了无掩膜YBCO薄膜激光化学刻蚀的表面特性及其变化规律,为YBCO激光化学刻蚀技术中图形形状控制、刻蚀时间选择和激光功率调节等提供了重要的实验结论.研究发现:在激光辐照下,YBCO薄膜的液相刻蚀速率大大加快,将极大改善刻蚀中的横向钻蚀情况,并提高图形边缘的侧壁陡峭度,且整个过程中的刻蚀速率呈现加快趋势;无掩膜时,YBCO表面刻蚀程度持续过渡,激光光斑边界两侧并非严格分界;衬底铝酸镧(LaAlO3)的晶向对YBCO薄膜的表面刻蚀特征有较大影响,沿LaAlO3晶向方向的刻蚀程度高于非晶向方向.     

高温超导YBCO薄膜及其制备

概述了高温超导YBCO(Y1Ba2Cu3O7-x)薄膜的基本性质、应用及制备技术的发展。介绍了脉冲激光沉积(PLD)与磁控溅射(MS)等的基本原理、工艺特点和最新发展情况。YBCO薄膜应用于超导电子器件中表现出优良的性能,如超导量子干涉仪(SQUID)等。     

快速热退火对纳米晶粒SnO2薄膜性质的影响

以SnCl2·2H2O及无水乙醇为原料,利用溶胶-凝胶法在快速热退火下制备了SnO2纳米薄膜,研究了快速热退火(RTA)对SnO2薄膜性质的影响.采用X射线衍射谱(XRD)、扫描电子显微镜(SEM),研究了薄膜的晶粒尺寸、微结构、表面形貌与快速热退火条件的关联,用傅里叶变换红外光谱(FT-IR)和光致发光研究了薄膜的光学性质.结果表明,快速热退火(RTA)温度对薄膜的光学性质、晶粒尺寸和薄膜的结构形态均有较大的影响.     

Magnetic shielding effects in Ag-doped and pure YBa2Cu3O7 − x thin films probed by non-resonant microwave absorption

A non-resonant microwave absorption technique is used to study the magnetic shielding effects in Ag-doped and pure YBa₂Cu₃O_{7 − x}(YBCO) thin films for small modulating fields. While Ag-doped YBCO thin films show good shielding for small modulating fields (≈ 1 Oe) until 60 K, the pure YBCO films show significant shielding effect only up to 20 K. We interpret these results in terms of better grain alignment in Ag-doped YBCO films as compared to pure YBCO films, which can lead to better shielding effects.     

Preparation and Flux-Pinning Properties of Multilayered Yttrium Barium Copper Oxide Thin Films Containing Alternating Barium Zirconate and Yttria Nanostructures

Multilayered yttrium barium copper oxide (YBCO) thin films grown by the pulsed laser deposition technique provide the possibility for independently tailoring the nanoscale artificial pinning centers embedded in individual layers. This enables engineering of artificial pinning centers in YBCO thin films for optimizing their flux-pinning properties. In this work, we combined barium zirconate (BaZrO₃) and yttria (Y₂O₃) nanostructures into multilayered YBCO thin films by alternating ablation of YBCO + BaZrO₃ and YBCO + Y₂O₃ composite targets. The layers containing BaZrO₃ nanostructures have a different thickness from those containing Y₂O₃ nanostructures. A highly epitaxial multilayered YBCO thin film, comprising five alternating layers of YBCO + BaZrO₃ and YBCO + Y₂O₃, has been prepared on a lanthanum aluminate (LaAlO₃) (100) substrate. This multilayered YBCO thin film exhibited strong flux-pinning properties. This work provides a preliminary step towards engineering of artificial pinning centers in YBCO thin films.     

Possible three-terminal device with YBCO angle grain boundary

The DC and AC Josephson effects were observed in YBa₂Cu ₃O_7-a (YBCO) bridges with metal-organic chemical vapor deposited (MOCVD) thin films on (100)MgO substrates. In TEM observations and X-ray analysis, the angle grain boundaries (AGBs) in these films were observed. Josephson junction resulting from the AGBs showed the semiconducting barrier junction property dominantly, and the AGBs consisted of YBCO with oxygen deficiency. Based on these results, the authors propose a three-terminal device with the Josephson junction. The Josephson junction can be prepared by depositing an epitaxial YBCO thin film with one AGB on a bicrystal (100)SrTiO₃ or (100)Si substrate, and the insulated gate for the application of electric field to the AGB is formed over the junction. The supercurrent in the Josephson junction is controlled by the electric field effect of the semiconducting AGB in the junction     

准分子激光扫描淀积PZT/YBCO结构铁电薄膜

利用脉冲准分子激光（工作气体ＸｅＣｌ，波长３０８ｎｍ，脉宽２８ｎｓ）在外延ＹＢＣＯ／ＬａＡｌＯ３（１００）单晶基片上淀积了Ｐｂ（Ｚｒ０．５５Ｔｉ０．４５）Ｏ３铁电薄膜，ＹＢＣＯ薄膜既为生长高取向ＰＺＴ薄膜提供了晶体匹配条件，同时也为ＰＺＴ铁电薄膜提供了下电极。讨论了工艺参数对晶相结构和表面形貌的影响。用Ｘ射线衍射表征了该多层膜的晶相结构，扫描电镜观察其表面形貌。ＰＺＴ铁电薄膜的剩余极化为２１μＣ／ｃｍ２，矫顽场为６５ｋＶ／ｃｍ。     

Study of high-quality epitaxial YBCO thin films grown directly on Y-Cut LiNbO3

Pulsed laser deposition was used to deposit high-quality YBa₂Cu₃O_7-δ (YBCO) thin films directly on y-cut LiNbO₃ substrates. The as-deposited YBCO films had a high degree of in-plane orientation and showed superconducting transition temperature (T_co) at 91K with a transition width of less than IK. Transport critical current densities were found to be ∼10⁶ A/cm² at 77K and zero field. An ion beam minimum channeling yield of 16% was obtained for YBCO films, indicating high crystallinity. High-resolution transmission electron microscopy studies showed that the interface between the film and the substrate was quite smooth and free from interfacial interdiffusion. The defects in thin films are also identified. The work showed that high-quality high T_c thin films can be deposited directly on LiNbO₃. Novel devices based on the properties of both YBCO and LiNbO₃ could be realized based on these results.     

LaNiO3 and Cu3Ge contacts to YBa2Cu3O7-x films

Metallization of high-T_c superconductors using low resistivity metal oxides and Cu-Ge alloys has been investigated on high quality pulsed laser deposited epitaxial YBa₂Cu₃O_7-x (YBCO) films. Epitaxial LaNiO₃ (LNO) thin films have been grown on YBCO films at 700°C using pulsed laser deposition. The specific resistivity of LNO was measured to be 50 μΩ-cm at 300K which decreases to 19 μΩ-cm at 100K indicating good metallicity of the LNO films. The contact resistance of LNO-YBCO thin film interface was found to be reasonably low (of the order of 10^-4Ω-cm² at 77K) which suggests that the interface formed between the two films is quite clean and LNO can emerge as a promising metal electrode-material to YBCO films. A preliminary investigation related to the compatibility of Cu₃Ge alloy as a contact metallization material to YBCO films is discussed. The usage of other oxide based low resistivity materials such as SrRuO₃ (SRO) and SrVO₃ (SVO) for metallization of high-T_c YBCO superconductor films is also discussed.     

高温超导YBa2Cu3O7薄膜的颗粒,杂相生长机制研究

ＹＢａ２Ｃｕ３Ｏ７（ＹＢＣＯ）高温超导薄膜是重要的超导电子器件应用的材料，它们的质量对器件的运行性能至关重要。薄膜表面的颗粒使表面微波性能变坏，但有些生长在ＹＢＣＯ薄膜基体内部的小颗粒，会使薄膜的临界电流密度升高。     

Thin film Y-Ba-Cu-O/Ag composites for fluxonic devices

We have investigated thin film composites of YBa₂Cu₃O₇ (YBCO) with Ag for fluxonic device applications. YBCO/Ag composite films are produced by first depositing a layer of Ag onto a substrate and then heating the film to the YBCO deposition temperature of 680°C or higher. YBCO is deposited by off-axis sputtering onto the Ag-coated substrate. The resulting YBCO/Ag film is a composite of YBCO with well-defined Ag regions several microns in size. Scanning electron micrograph images of the films' surfaces show a background of smooth YBCO grains dotted with Ag clusters. For a wide range of increasing Ag composition, the transition temperatures of the composite films on SrTiO₃ remain high, while the critical current densities have been reduced as much as 65 times. On MgO substrates, critical current density has been reduced by more than four orders of magnitude. Also on MgO, significant voltage response is seen in external magnetic fields of less than 1 mT. These measurements suggest that the films may be arrays of superconductor-normal-superconductor (SNS) junctions formed by weakly coupled YBCO grains with Ag in the grain boundaries. The field responsivity and low critical current densities of these composites make them potentially useful for fabrication of fluxonic devices