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MgO(111)上NbN和AlN薄膜的生长研究 总被引:2,自引:0,他引:2
在制备NbN/AlN/NbN隧道结的工艺过程中,为了获得具有优质单晶结构的NbN薄膜,我们在MgO(111)基片上探索了直流溅射法制备NbN薄膜的生长工艺条件,XRD研究分析表明,我们获得了单晶结构良好的NbN薄膜;为了支持作为上电极的NbN薄膜的生长,也需要良好的AlN薄膜用作势垒层,我们采用射频磁控溅射设备和纯净的Al靶对AlN薄膜进行了制备研究.实验结果表明,所获得的AlN薄膜具有六方c-轴取向,并讨论了衬底和薄膜界面处可能的结构情况. 相似文献
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我们开展了高临界电流密度的NbN约瑟夫森结的制备和特性研究.利用直流磁控溅射方法在单晶MgO(100)衬底上外延生长NbN/AlN/NbN三层膜,并使用微加工工艺制备了NbN约瑟夫森隧道结,在液氦温度下对NbN约瑟夫森结的电流-电压特性进行了测量,实验结果表明,NbN约瑟夫森结具有良好的隧穿特性,其临界电流密度J_c为10 kA/cm^2,质量因子大于10,能隙是5.7 mV,这些实验结果为基于NbN结的超导数字电路研究奠定了坚实的基础. 相似文献
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采用射频磁控溅射法制备了NbN,AlN单层膜及不同调制周期的AlN/NbN纳米结构多层膜,采用X射线衍射仪、小角度X射线反射仪和高分辨透射电子显微镜等对薄膜进行了表征.结果表明:单层膜AlN为六方结构,NbN为面心立方结构;AlN/NbN多层膜中AlN为六方结构,NbN为面心立方结构,界面处呈共格状态,其共格关系为c-NbN(111)面平行于h-AlN(0002)面,晶格错配度为013%.热力学计算表明:AlN/NbN多层膜中不论AlN层与NbN层的厚度如何,AlN层均不会形成亚稳的立方AlN,而是形成
关键词:
AlN/NbN纳米结构多层膜
共格外延生长
异结构 相似文献
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体声波滤波器由于其低插损、小尺寸、高带外抑制等特性,随着第三代移动通信以及蓝牙技术的发展而得到广泛研究,而MEMS技术和压电薄膜制备技术的进一步发展使高性能的体声波滤波器制作成为可能. 我们以单晶MgO作为器件衬底,MgO/NbN多层结构作为AlN薄膜体声波器件的反射器,NbN/AlN/NbN三层结构为谐振器.在这样的多层结构的设计中由于各种材料之间的晶格失配小,可以获得从几十纳米到几百纳米厚度不等的单晶AlN薄膜.通过控制AlN薄膜和NbN薄膜的不同厚度,可以获得不同频段范围的谐振器. 压电薄膜的质量,以及体声波在多层结构界面上的能量损耗,直接影响到谐振器电学性能.基于AlN材料的压电性能,设计了NbN/AlN/NbN三层结构的谐振器,并进行了数值模拟. 相似文献
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NbN superconductor and wide band gap AlN thin films were deposited using sputtering at room temperature. Study of the nitride interfaces are forerunner to the growth Josephson junctions that are considered able to work in the terahertz frequency. We find that to be compatible with lithography technology and to have a high critical transition temperature, the substrate should not be overheated, and this means working in low power regime to limit the induced heating of the plasma. X-ray photoelectron spectroscopy and X-ray diffraction analysis were performed on samples deposited on crystalline, amorphous, flexible, and nanostructured substrates. The experimental results suggest us how to improve the deposition process in order to obtain the best nitride films as well as NbN/AlN/NbN trilayers for Josephson junction applications. 相似文献
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体声波滤波器由于其低插损、小尺寸、高带外抑制等特性,随着第三代移动通信以及蓝牙技术的发展而得到广泛研究,而MEMS技术和压电薄膜制备技术的进一步发展使高性能的体声波滤波器制作成为可能.我们以单晶MgO作为器件衬底,MgO/NbN多层结构作为AIN薄膜体声波器件的反射器,NBN/AIN/NbN三层结构为谐振器.在这样的多层结构的设计中由于各种材料之间的晶格失配小,可以获得从几十纳米到几百纳米厚度不等的单晶AIN薄膜.通过控制AIN薄膜和NbN薄膜的不同厚度,可以获得不同频段范围的谐振器.压电薄膜的质量,以及体声波在多层结构界面上的能量损耗,直接影响到谐振器电学性能.基于AIN材料的压电性能,设计了NBN/AIN/NBN三层结构的谐振器,并进行了数值模拟. 相似文献
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We have studied the temperature dependence of the in-plane resistivity of NbN/AlN multilayer samples with varying insulating layer thickness in magnetic fields up to 7 T parallel and perpendicular to the films. The upper critical field shows a crossover from 2D to 3D behavior in parallel fields. The irreversibility lines have the form (1-T/T(c))(alpha), where alpha varies from 4 / 3 to 2 with increasing anisotropy. The results are consistent with simultaneous melting and decoupling transitions for the low anisotropy sample, and with melting of decoupled pancakes in the superconducting layers for higher anisotropy samples. 相似文献
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采用射频磁控溅射方法制备单层TaN,NbN和TiN薄膜和不同调制周期的TaN/TiN和NbN/TiN纳米多层膜.薄膜采用X射线衍射仪、高分辨率透射电子显微镜和显微硬度仪进行表征.结果表明TaN/TiN和NbN/TiN纳米多层膜在一定的调制周期范围内均呈共格界面,相应地均出现了超硬效应,且最大硬度值接近.分析了TaN/TiN与NbN/TiN纳米多层膜的超硬机理,TaN/TiN的晶格错配度与NbN/TiN的接近,但TaN/TiN的弹性模量差与NbN/TiN的有一定的差别,表明由于晶格错配使共格外延生长在界面处
关键词:
TaN/TiN纳米多层膜
NbN/TiN纳米多层膜
外延生长
超硬效应 相似文献
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H. van de Stadt J. Mees Z. Barber M. Blamire P. Dieleman Th. de Graauw 《International Journal of Infrared and Millimeter Waves》1996,17(1):91-104
We describe heterodyne mixing experiments with NbCN/Nb quasi-particle tunnel junctions at submillimeter wavelengths. In this wavelength range junctions with niobium nitride as superconducting material are promising because of the high gap voltage, about 5.7 mV, as compared to 3 mV for the more commonly used niobium. As a first step towards all-NbN junctions we investigate the development of junctions with a NbN base electrode and a Nb upper electrode. We present results from samples with two different insulating barriers: aluminum oxide and magnesium oxide. Measured noise temperatures range from 500 K at 345 GHz and 1600 K at 482 GHz to 8500 K at 644 GHz. These results are about one order of magnitude worse than the best results obtained with all-Nb junctions. The difference can be attributed partly to the relatively high radio-frequency (rf) losses in NbN films as compared to Nb. Also sensitivity is reduced because of the relatively high leakage current in the sub-gap region of the I-V curve of the junction. 相似文献
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We measured shot noise and submillimeter-wave response in a superconducting NbN tunnel junction that had a subharmonic gap structure on the current-voltage (I-V) curve. We found that the observed effective charge, defined from the noise-current ratio, tends to a steplike function of voltage. In the presence of submillimeter-wave radiation of frequency v, novel step structures spaced by hv/2e below and above the half-gap voltage clearly appeared on the I-V curve, overlapping the ordinary photon-assisted tunneling steps spaced by hv/e. Observation of these features provides clear evidence that coherent multiple Andreev reflection processes occur in the NbN tunnel junction with low barrier transparency. 相似文献
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具有超导绝缘相变特性的纳米多孔超导薄膜在红外光电探测领域有着潜在的应用价值,而其在红外波段的宽带光响应特性研究目前尚未见报道.为此,本文以纳米多孔氮化铌(NbN)薄膜为主要对象,研究了其在780—5000nm的近、中红外波长范围内的光响应特性.首先,采用Drude模型拟合的方法,不仅将对实验数据拟合的精度提高了约17%,而且得到了中红外波段的NbN光学参数;进而,采用时域有限差分法分析了加载纳米多孔NbN薄膜的背面对光器件的光响应特性,并给出了能够将纳米多孔薄膜简化为均匀薄膜的Bruggeman等效模型,从而可以将纳米多孔NbN薄膜光响应特性的仿真维度由三维降为一维;最后,基于等效模型和传输矩阵法,对加载纳米多孔NbN薄膜的背面对光器件在近、中红外波段内的光吸收特性进行了优化设计.结果表明:一方面,使用Bruggeman等效模型简化设计过程并不会影响最终结果的正确性;另一方面,仅仅是加载较为简单的光学腔,即可使得探测器的薄膜光吸收率在近、中红外宽带设计时均大于82%,在近红外双波长设计时均大于93.7%,并且多孔薄膜结构具有天然的极化不敏感特性. 相似文献