高温退火对蓝宝石基片的表面形貌和对CeO2缓冲层以及Tl-2212超导薄膜生长的影响

研究了蓝宝石(1102)基片在不同温度和时间下退火时表面形貌和表面相结构的变化,以及它对CeO₂缓冲层和Tl-2212超导薄膜生长的影响.原子力显微镜(AFM)研究表明,在流动氧环境中1000℃温度下退火,蓝宝石(1102)的表面首先局部区域形成台阶结构,然后表面形成叠层台阶结构,随着退火时间的延长,表面发生了台阶合并现象,表面形貌最终演化为稳定的具有光滑平台的宽台阶结构.XRD测试表明,通过高温热处理可以大幅度提高蓝宝石基片表面结构的完整性.在1000℃温度下热处理20 h的蓝宝石 关键词： Tl-2212超导薄膜 蓝宝石 缓冲层     

高温退火对蓝宝石基片的表面形貌和对CeO缓冲层以及Tl-2212超导薄膜长的影响

研究了蓝宝石(1102)基片在不同温度和时间下退火时表面形貌和表面相结构的变化,以及它对CeO2缓冲层和T1-2212超导薄膜生长的影响.原子力显微镜(AFM)研究表明,在流动氧环境中1000℃温度下退火,蓝宝石(1102)的表面首先局部区域形成台阶结构,然后表面形成叠层台阶结构,随着退火时间的延长.表面发生了台阶合并现象,表面形貌最终演化为稳定的具有光滑平台的宽台阶结构.XRD测试表明,通过高温热处理可以大幅度提高蓝宝石基片表面结构的完整性.在1000℃温度下热处理20 h的蓝宝石(1102)基片上可以生长出具有面内取向的CeO2(001)缓冲层.在具有缓冲层的蓝宝石基片上可以制作出高质量c轴织构的外延11-2212超导薄膜,其临界转变温度(Tc)为104.7 K,液氮温度下临界电流密度(Jc)达到3.5 MA/cm2,微波表面电阻R(77 K,10 GHz)约为390μΩ.     

高温退火对蓝宝石基片的表面形貌和对CeO2缓冲层以及Tl-2212超导薄膜生长的影响

研究了蓝宝石(1102)基片在不同温度和时间下退火时表面形貌和表面相结构的变化，以及它对CeO₂缓冲层和Tl-2212超导薄膜生长的影响.原子力显微镜(AFM)研究表明，在流动氧环境中1000℃温度下退火，蓝宝石(1102)的表面首先局部区域形成台阶结构，然后表面形成叠层台阶结构，随着退火时间的延长，表面发生了台阶合并现象，表面形貌最终演化为稳定的具有光滑平台的宽台阶结构.XRD测试表明，通过高温热处理可以大幅度提高蓝宝石基片表面结构的完整性.在1000℃温度下热处理20 h的蓝宝石     

蓝宝石基片上制备双面Tl_2Ba_2CaCu_2O_8超导薄膜

在蓝宝石基片上,以CeO2为缓冲层制备了高质量的双面Tl2Ba2CaCu2O8(Tl-2212)超导薄膜。以金属铈靶作为溅射源生长了c轴取向的CeO2缓冲薄膜,并对CeO2薄膜进行了高温处理,有效改善了其结晶质量和表面形貌。采用两步法制备了双面的Tl-2212超导薄膜。XRD测试显示,薄膜为纯的Tl-2212相,且其晶格c轴垂直于衬底表面。超导薄膜的Tc为106K,Jc(77K,0T)为3.5MA/cm2,微波表面电阻Rs(77K,10GHz)为390μΩ。     

Tl系超导薄膜金属涂层的生长与特性研究

我们研究了Tl-2212超导薄膜在带有YSZ/CeO2缓冲层和带有CeO2/YSZ/CeO2缓冲层的Ni金属RABiTS基带上的生长情况.基带上的缓冲层是采用PLD方法制备的,Tl-2212薄膜的制备采用了磁控溅射和后热处理两步方法.XRD 实验结果表明,Tl-2212薄膜都具有很好的C轴垂直于膜面的织构,并具有双向外延生长特性.在CeO2/YSZ/CeO2/Ni基带上制作的Tl-2212薄膜的Tc达到102.8 K,Jc(77 K,0 T)达到2.6 MA/cm2;在YSZ/CeO2/Ni基带上薄膜Tc可达97.7 K,Jc(77 K,0 T)也可以达到0.45 MA/cm2.     

在RABiTS基带上制备Tl-2212超导薄膜

我们研究了Tl-2212超导薄膜在带有YSZ/CeO2缓冲层和带有CeO2/YSZ/CeO2缓冲层的Ni金属RABiTS基带上的生长情况.基带上的缓冲层是采用PLD方法制备的,Tl-2212薄膜的制备采用了磁控溅射和后热处理两步方法.XRD 实验结果表明,Tl-2212薄膜都具有很好的c轴垂直于膜面的织构,并具有双向外延生长特性.在CeO2/YSZ/CeO2/Ni基带上制作的Tl-2212薄膜的Tc达到102.8 K,Jc(77K,0T)达到2.6 MA/cm2;在YSZ/CeO2/Ni基带上薄膜的Tc可达97.7K,Jc (77K,0T)也可以达到0.45MA/cm2.     

在RABiTS基带上制备Tl-2212超导薄膜

我们研究了Tl-2212超导薄膜在带有YSZ／CeO2缓冲层和带有CeO2／YSZ／CeO2缓冲层的Ni金属RABiTS基带上的生长情况．基带上的缓冲层是采用PLD方法制备的，Tl-2212薄膜的制备采用了磁控溅射和后热处理两步方法．XRD实验结果表明，Tl-2212薄膜都具有很好的c轴垂直于膜面的织构，并具有双向外延生长特性．在CeO2／YSZ／CeO2／Ni基带上制作的Tl-2212薄膜的Tc达到102．8K，Jc（77K，0T）达到2．6MA／cm^2；在YSZ／CeO2／Ni基带上薄膜的Tc可达97．7K，Jc（77K，0T）也可以达到0．45MA／cm^2．     

多层高温超导薄膜研究

文中以LaAlO3为衬底,制作了一层Tl-2212高温超导薄膜,并在薄膜上生长一层较薄的CeO2缓冲层,然后再在上面生长一层Tl-2212高温超导薄膜。经过测量,研究了多层膜结构对超导薄膜临界电流密度的影响。结果显示,在缓冲层的结晶过程中超导薄膜的晶格受到影响,结晶过程中的处理很容易诱导上面一层Tl-2212超导薄膜产生杂相,导致临界电流密度降低。     

在MgO衬底上制作Tl2Ba2CaCu2O8超导薄膜

在MgO衬底上,利用共蒸发方法制备DyBa2Cu3O7作为缓冲层,再利用磁控溅射和后处理方法,制备了Tl2Ba2CaCu2O8超导薄膜.X射线衍射θ～2θ及φ扫描结果表明Tl-2212薄膜、Dy-123薄膜与衬底MgO呈外延生长关系.制备的Tl-2212薄膜Tc＝105.5K,液氮温度下临界电流密度Jc＝2.5×106A/cm2.     

Tl-2212超导薄膜的制备

以铝酸镧晶体为基片,采用两步法制备Tl-2212超导薄膜,包括在低温(150℃)下利用激光脉冲沉积(PLD)工艺沉淀Ba2CaCu2Ox非晶前驱体薄膜和在高温(740～830℃)下前驱体薄膜的铊化结晶、取向生长过程.实验结果表明所制得的膜的相组成为Tl-2212,表面存在大量均匀分布的成分为Tl2Ba2CaCu2Ox的亚微米颗粒.其零电阻温度为101K.薄膜与基片之间界面清晰,没有过渡层,薄膜具有良好的c取向外延条纹.     

T1系超导薄膜金属涂层的生长与特性研究

我们研究了T1-2212超导薄膜在带有YSZ／CeO2缓冲层和带有Ce02／YSZ／CeO2缓冲层的Ni金属RABiTS基带上的生长情况．基带上的缓冲层是采用PLD方法制备的，T1-2212薄膜的制备采用了磁控溅射和后热处理两步方法．XRD实验结果表明。T1-2212薄膜都具有很好的C轴垂直于膜面的织构，并具有双向外延生长特性．在CeO2／YSZ／CeO2／Ni基带上制作的T1-2212薄膜的Tc达到102．8K，J,（77K,0T）达到2.6MA／cm^2；在YSZ／CeO2／Ni基带上薄膜Tc可达97．7K，Jc（77K,0T）也可以达到0．45MA／cm^2.     

MgO单晶基片上YBCO高温超导薄膜的制备

在2英寸MgO(001)单晶基片上,采用直流溅射法,通过基片高温退火,成功制备了性能优越的YBa2C3O7-δ(YBCO)双面超导薄膜,能够满足超导滤波器的设计要求。X射线衍射(XRD)分析表明经过退火的基片上生长的YBCO薄膜与基片有单一的外延取向关系;用原子力显微镜(AFM)和高能电子衍射(RHEED)分析高温退火对基片表面状况的改变。结果表明制备的YBCO薄膜具有很好的超导电性,薄膜临界电流密度Jc(77K,0T)≈2.5×106A/cm2,微波表面电阻Rs(10GHz,77K)≈0.16mΩ。     

采用快速升温烧结方法生长Tl-1223超导薄膜的研究

报道了在铝酸镧(00l)衬底上生长Tl-1223超导薄膜的快速升温烧结方法以及铊(Tl)源陪烧靶的配比对Tl-1223薄膜晶体结构的影响.扫描电子显微镜观测表明,采用快速升温烧结方法生长的Tl-1223超导薄膜具有致密的晶体结构.X-射线衍射等测试表明,采用合适配比的陪烧靶在氩气环境下可以制备出纯c轴取向的Tl-1223超导薄膜,充氧退火后的薄膜具有较好的电学性能,其临界转变温度T_(c onset)达到116K,临界电流密度达到1.5MA/cm~2(77 K,0 T).实验结果表明,采用这一新的烧结方法制备Tl系超导薄膜具有升降温时间和恒温时间短、生产成本低等特点.     

Fabrication of Tl_2Ba_2CaCu_2O_8 superconducting films without thallium pellets

A new improved two-step method in fabricating Tl_2Ba_2 CaCu_2O_8(Tl-2212) thin films is presented in this paper. In the first process of dc magnetron sputtering, the thallium content in the precursor film is largely increased by adjusting the ratio of thallium in the sputtering targets. After the second annealing process in the absence of additional thallium pellets or powder source, high-quality Tl-2212 thin films can be obtained. The proper content of thallium in the precursor film provides a relatively stable atmosphere to guarantee the growth of Tl-2212 film. This method avoids the repeated production of the thallium pellets in the post-annealing process, the repeatability and controllability of the experiment are greatly improved. X-ray diffraction(XRD) scans show that all of the sharp peaks of the sample films can be assigned to the(00 l) peaks of Tl-2212 phase. The highest superconducting critical temperature(Tc) of the films is 105 K and the critical current density(Jc) can achieve 1.93 MA/cm2 in zero magnetic field at 77 K for a 600 nm film.     

Deposition of MgO films by pulsed mid-frequency magnetron sputtering

MgO films were deposited by pulsed mid-frequency magnetron sputtering from metallic targets in the mixture of Ar and O₂ gas. The surface morphology, crystalline structure, and optical properties were characterized by using atomic force microscopy (AFM), X-ray diffraction (XRD), and spectroscopic ellipsometry, respectively. The secondary electron emission coefficients of MgO films were measured by using a self-made apparatus in He gas. A pronounced hysteresis phenomenon of target voltage, current, and deposition rate with increasing and decreasing O₂ flow rate was observed. The structure of films deposited at a metallic mode changes from Mg phase to the mixed Mg and MgO phase, and the films have a very rough surface. All the films deposited at oxide mode have high transparency and smooth surface, and show (2 2 0) preferred orientation growth. The refractive index and extinction coefficient at a wavelength of 670 nm for MgO films deposited at oxide mode with a O₂ flow rate of 3 sccm are 1.698 and 1.16×10⁻⁴, respectively. The secondary emission coefficient at a E/p of 57.8 V/(cm Torr) for MgO films deposited at a O₂ flow rate of 3 sccm is 0.16, which is higher than that of MgO films deposited by e-beam evaporation.     

Surface segregational behaviour studied as an effect of thickness by SIMS and AFM in annealed PS-PMMA blend and block copolymer thin films

The surface behaviour of a two-phase polymer mixture depends on the chemical structure of the polymer components, the interaction between the two polymers and the processing conditions. The microscopic morphology and the surface composition need to be known in order to fully utilize the thin film properties. The technique of static time-of-flight secondary ion mass spectrometry (ToF-SIMS) is used to obtain the molecular surface composition of thin films of blends and block copolymers. The depth profiling tool of Nano-SIMS, a dynamic SIMS technique, helps to provide the chemical mapping of the surface in 2D and 3D. The surface morphology is investigated using AFM. Thin films of PS and PMMA diblock copolymers with molecular weight of 12K-12K and 10K-10K and blends of PS/PMMA (10K/10K) for thicknesses ranging from 5 nm to 50 nm are examined. For the blends, the ToF-SIMS spectra for all the thicknesses show the same behaviour of a high increase of PMMA on the surface after annealing. Nano-SIMS images reveal the formation of nanostructures on the annealed surfaces and AFM studies show these nanostructures to be droplets having distinct phase shift from the surrounding matrix. The droplet dimensions increase with the increase of the thickness of the film but the absolute intensity from the ToF-SIMS spectra for all the annealed films remains almost the same. For the copolymers, the ToF-SIMS spectra show that there is a decrease of PMMA on the surface for the annealed films when compared to the as-cast ones. AFM morphology reveals that, for different thicknesses, annealing induces different topographical features like droplets, holes, spinodal patterns, etc. but with no distinct phase shift between the patterns and the surrounding matrix. The two different copolymers of comparable molecular weight are found to exhibit very different topography even when the thickness of the films remained the same. The surface composition from the ToF-SIMS data, however, was not found to vary even when the topography was completely different.     

二氧化锆薄膜制备及其特性测量

在室温下采用电子束蒸发的办法制备二氧化锆（ZrO2）薄膜。 借助紫外分光光度计、原子力显微镜（AFM）、X射线衍射（XRD）等方法研究了薄膜的透射率和表面结构。 同时研究了不同退火温度对薄膜物理性质的影响。在退火温度700,900,1 050 ℃时显微镜图像没有明显差别。随着退火温度的变大,薄膜表面的晶粒的直径逐渐变大,但粒径均在25 nm左右。当退火温度达到1 150 ℃时,粒径变得很大(约400 nm)。在700,900,1 050 ℃下退火后的薄膜的X射线衍射谱没有明显差别。在退火温度1 150 ℃下出现了较高的峰,研究结果表明:退火温度的增加,大量大粒径二氧化锆单晶晶粒出现,使得二氧化锆薄膜的漏电流增大,从而导致其热稳定性变差。