共查询到20条相似文献,搜索用时 156 毫秒
1.
利用混合物理化学气相沉积法在6H-SiC(001)衬底上制备干净的MgB2超导超薄膜.在本底气体压强、载气氢气流量等条件一定的情况下,改变B2H6流量及沉积时间,制备得到不同厚度的系列MgB2超薄膜样品,并研究了超导转变温度Tc、剩余电阻率ρ(42K)、上临界磁场Hc2等与膜厚的关系.该系列超薄膜沿c轴外延生长,随膜厚度的变小,Tc(0)降低,ρ(42K)升高.膜在衬底上的生长遵循Volmer-Weber岛状生长模式.对于厚度为7.5 nm的MgB2超薄膜,Tc(0) =32.8 K,ρ(42K) =118 μΩcm,是迄今为止所观测到的厚度为7.5 nm的MgB2超薄膜最高的Tc值;对于厚度为10 nm的MgB2膜,Tc(0)=35.5 K,ρ(42K)=17.7 μΩcm,上临界磁场μ0Hc2估算为12 T左右,零磁场、4 K时的临界电流密度Jc=1.0×107 A/cm2,是迄今为止10 nm厚MgB2超薄膜的最高Jc值,且其表面连接性良好,均方根粗糙度为0.731 nm.这预示MgB2超薄膜在超导纳米器件上具有广阔的应用前景.
关键词:
2超薄膜')" href="#">MgB2超薄膜
薄膜生长
氢气流量
混合物理化学气相沉积 相似文献
2.
采用第一性原理计算方法,研究了三元氢化物Y-Si-H体系在高压下的晶体结构、电子性质及超导性质,发现了热力学稳定的YSiH7、YSiH9、YSi2H12和YSiH18,以及热力学亚稳的YSi2H13、YSi2H14和Y2SiH17。电子性质计算表明,YSiH7为绝缘体,YSi2H13为半导体,其余氢化物均具有金属特性。通过麦克米兰方程估算超导转变温度(Tc)发现,YSi2H12具有最高的Tc,在100 GPa下为43.5 K。YSi2H14的动力学稳定压力可降至40 GPa,Tc为23.8 K,是Y-Si二元化合物中最高Tc的2倍,... 相似文献
3.
4.
利用混合物理化学气相沉积法(HPCVD)在MgO(111)衬底上制备了干净的MgB2超导超薄膜. 在背景气体压强, 载气氢气流量以及沉积时间一定的情况下, 改变B2H6的流量, 制备得到不同厚度系列的MgB2超导薄膜样品, 并测量了其超导转变温度 Tc, 临界电流密度Jc等临界参量. 该系列超导薄膜沿c轴外延生长, 表面具有良好的连接性, 且有很高的超导转变温度Tc(0) ≈ 35-38 K和很小的剩余电阻率ρ(42 K) ≈ 1.8-20.3 μΩ·cm-1. 随着膜厚的减小而减小, 临界温度变低, 而剩余电阻率变大. 其中20 nm的样品在零磁场, 5K时的临界电流密度Jc ≈ 2.3×107 A/cm2. 表明了利用HPCVD在MgO(111)衬底上制备的MgB2超薄膜有很好的性能, 预示了其在超导电子器件中广阔的应用前景.
关键词:
MgO(111)衬底
2超薄膜')" href="#">MgB2超薄膜
混合物理化学气相沉积 相似文献
5.
应用一光学变换传输系统,使得激光束通过该系统后可绕一定的半径旋转,旋转的激光束消融淀积大面积YBa2Cu3O7超导薄膜。以其片中心处的超导薄膜厚度的90%为均匀区域界限,激光旋转半径为0,3mm和9mm时,淀积的超导薄膜厚度均匀区域面积分别为0.14cm^2、0.82cm^2、6.79cm^2。 相似文献
6.
7.
8.
9.
10.
测量了块体金属玻璃Zr46.75Ti8.25Cu7.5Ni10Be27.5在退火前后其电阻值随温度的变化,测量的温度范围为1.5—300K.样品在退火前后都发现有超导现象.零磁场下其超导转变温度Tc分别为1.84和3.76K.在5—300K温度范围内,原始样品具有负的电阻温度系数.如果取Zr, Ti, Cu, Ni及Be分别贡献出1.5, 1.5, 0.5, 0.5及两个传导
关键词:
块体金属玻璃
超导
电阻温度系数 相似文献
11.
A. Tsukada K. E. Luna R. H. Hammond M. R. Beasley J. F. Zhao S. H. Risbud 《Applied Physics A: Materials Science & Processing》2011,104(1):311-318
We report the effects of growth conditions on the superconducting properties of FeSe films epitaxially grown on LaAlO3 substrates by pulsed laser deposition (PLD). Customary materials characterization techniques [X-ray diffraction (XRD), in-situ
X-ray photoelectron spectroscopy (XPS), in-situ ultra-violet photoelectron spectroscopy (UPS), and scanning electron microscopy
(SEM)] revealed the films had a c-axis oriented tetragonal structure with lattice constants dependent on the growth temperature (varied from 100 to 600°C).
The standard four-point probe method was used to measure the resistivity and superconducting transitions. Films grown at 400–550°C
showed a clear superconducting onset but no zero resistance down to 2 K. The highest superconducting onset temperature (TconsetT_{\mathrm{c}}^{\mathrm{onset}}) of 8 K was observed in films grown at 500°C and the onset temperature was clearly correlated to the ratio of the lattice
constants (c/a). As the thickness of the FeSe films increased from 27 nm to 480 nm, TconsetT_{\mathrm{c}}^{\mathrm{onset}} also increased as the strain in the system was relaxed. 相似文献
12.
报道了利用电子束蒸发的Mg/B多层膜作为前驱体,然后退火制备MgB2薄膜的工作. 实验中发现,采用翻转膜面的退火处理方式可以有效地避免降温过程中Mg蒸气在薄膜表面形成的颗粒凝结,由此稳定地实现了面积为10 mm×10 mm,均匀、平整的超导薄膜的制备,Tc达35 K,转变宽度为0.8 K,在5 μm×5 μm的区域内薄膜的平均粗糙度小于10 nm. 为了便于后续器件制作过程中的微加工工艺,研究了膜厚小于1000 ?时薄膜的成相规律,发现当样品厚度减薄后,Tc会有明显降低. 通过调整前驱薄膜中的不同分层厚度,仍可实现转变温度达30 K以上、厚度约600 ?的MgB2薄膜,在20 K时的临界电流密度为2.4×106 A/cm2. 相似文献
13.
Congxin Ren Guoliang Chen Jianmin Chen Jie Yang Yijie Li Zhengxiu Chen Le Wang Leiming Xie Shichang Zou 《Applied Physics A: Materials Science & Processing》1991,52(3):203-205
Preparation of high T
c and high J
c YBa2Cu3O7– superconducting thin films by ion beam sputtering deposition is reported. The main factors affecting the composition of the films and the orientation of the crystal grains have been examined. Experimental results show that the Y, Ba and Cu composition of as-deposited films can be conveniently and accurately adjusted by a combined sputtering target which consists of a large sintered target of YBa2Cu3O7– and a small one that is Ba and Cu rich (YBa2.5Cu3.3Ox). Fabrication conditions of highly oriented superconducting thin films are described. YBa2Cu3O7– superconducting films with zero resistance at 88–90.5K and critical current density J
c (at 77K) of 1.5×105 A/cm2 are obtained. 相似文献
14.
A. V. Varlashkin S. I. Krasnosvobodtsev M. L. Chukharkin O. V. Snigirev A. V. Tsikunov N. P. Shabanova 《Technical Physics》2007,52(5):660-662
A method is presented for the deposition of smooth epitaxial high-T c superconducting films using a pulsed infrared YAG: Nd3+ laser and velocity filtration. This method is based on the removal of drops and solid particles from the flow of deposited substance with a fast shutter made of a rotating disk. The deposited smooth homogeneous YBa2Cu3O7?δ films have a critical temperature T c > 90 K. The surface concentration of drops is less than 3 × 102 cm?2, and their amount is decreased by more than six orders of magnitude. 相似文献
15.
A model is proposed for the thermal and electrical responses of films of the high-T
c superconducting material YBa2Cu3O77−x
to current and optical pulses. Numerical calculations are compared with experimental data for current pulses of duration
100 μs and laser pulses of duration 0.1 ns; this yields improved data on the thermal conductivity of thin YBa2Cu3O77−x
films (1.5–2 W/m·K) and thermal resistance of the film-substrate contact (5×10−8m2·K/W) in the neighborhood of the superconducting transition. This model can be used for optimizing the film structure parameters
and control regimes for switching elements for pulses lasting longer than 0.1 ns.
Zh. Tekh. Fiz. 69, 77–82 (October 1999) 相似文献
16.
High-T
c
superconducting thin films of Bi–Sr–Ca–Cu oxides were prepared by laser-induced plasma deposition of high-T
c
superconducting Bi2Sr2Ca1Cu2Ox and Bi2Sr2Ca2Cu3Ox targets in vacuum and a short post-annealing in air at 875°C. Thin films (thickness <500 nm) with a critical temperatureT
c
-onset of 95 K can be prepared on silicon substrate material with a SrTiO3 interface layer. The thin films were completely superconducting between 80 and 90 K. The stoichiometry transfer of superconducting target material by laser-induced plasma deposition was investigated. 相似文献
17.
N. V. Vostokov S. V. Gaponov B. A. Gribkov Yu. N. Drozdov D. V. Masterov V. L. Mironov Yu. N. Nozdrin E. E. Pestov 《Physics of the Solid State》2003,45(11):2025-2030
The surface morphology and superconducting properties of YBaCuO epitaxial films prepared through magnetron sputtering from targets of different cation composition were systematically studied. It was shown that small changes in the growth conditions and relatively small variations in the cation composition of the condensate noticeably affect the surface morphology of the films and their structural and superconducting properties, thus offering an efficient way of controlling the YBCO film parameters. It was found that the 90° off-axis configuration of the magnetron sputtering system permits realization of growth conditions in which the grown films do not contain CuO precipitates and exhibit good superconducting properties (Tc≥88 K, jc(77 K)≥4×106 A/cm2). 相似文献
18.
Biaxially textured YBa2Cu3O7−x (YBCO) films were grown on inclined-substrate-deposited (ISD) MgO-textured metal substrates by pulsed laser deposition. CeO2 was deposited as a buffer layer prior to YBCO growth. CeO2 layers of different thickness were prepared to evaluate the thickness dependence of the YBCO films. The biaxial alignment features of the films were examined by X-ray diffraction 2θ-scans, pole-figure, ?-scans and rocking curves of Ω angles. The significant influence of the CeO2 thickness on the structure and properties of the YBCO films were demonstrated and the optimal thickness was found to be about 10 nm. High values of Tc = 91 K and Jc = 5.5 × 105 A/cm2 were obtained on YBCO films with optimal CeO2 thickness at 77 K in zero field. The possible mechanisms responsible for the dependence of the structure and the properties of the YBCO films on the thickness of the CeO2 buffer layers are discussed. 相似文献
19.
High quality epitaxial YBa2Cu3O7-x thin films have been succcessfully prepared by dc magnetron sputtering deposition, on (100) and (110) aligned SrTiO3, LaAlO3 and yttria-stabilized zirconia (YSZ) substrates. The films showed zero resistance around 90 K and had a Jc (at 77 K, H=0) over 106A/cm2. It was found that superconducting properties and structures of the films were strongly dependent on oxygen pressure and substrate temperature. The epitaxial structure of the films have been studied by X-ray diffraction. Rutherford backscattering and channeling spectroscopy, X-ray double-crystal diffraction and transmission election microscopy. The experimental results demonstrated that the epitaxial YBa2Cu3O7-x films had excellent superconducting properties and quite perfect structure. 相似文献
20.
Production of YBa2Cu3O7−x superconducting thin films by pulsed pseudospark electron beam evaporation
H. P. Schölch P. Fickenscher T. Redel M. Stetter G. Saemann-Ischenko W. Benker W. Hartmann K. Frank J. Christiansen 《Applied Physics A: Materials Science & Processing》1989,48(4):397-400
Thin-film superconducting YBa2Cu3O7–x layers have been produced in a single-step process by pulsed electron beam evaporation from a stoichiometric 1-2-3 target. The films were produced at the 100 surface of SrTiO3 substrates heated to a temperature of approximately 1000 K in a pure oxygen atmosphere of about 10 Pa total pressure. After deposition the films were cooled in situ within 20 minutes to ambient temperature. At present, the films are polycrystalline and show a Tc,zero of 83 K with a transition width of 3–5 K. Critical current densities of 7·104 A/cm2 at 4.2 K and zero magnetic field have been achieved. The pulsed electron beams used in these experiments are produced by a pseudospark discharge; the estimated energy density deposited at the target surface by the electron beam is of the order of 4 J/cm2. 相似文献