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Structural Control due to Annealing and Superconducting Property of Mo Based Multilayer Thin Films

钼基多层薄膜退火和超导性能的结构控制

基本信息

批准号：
62550470
负责人：
NAKAJIMA Hideo
金额：
$ 1.22万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1987
资助国家：
日本
起止时间：
1987 至 1988
项目状态：
已结题

项目摘要

Multilayerd Mo/Si thin films have been prepared by a dual rf-magnetron sputtering technique. X-ray diffractometry shows that for the modulation wavelength 【.Ibdabar.】 shorter than 3 nm both Mo and Si sublayers are amorphous, while for 【.Ibdabar.】 longer than 3 nm, crystalline bcc structure appears in Mo sublayers. Interdiffusion in Mo/Si and MoN/SiN multilayer thin films has been studied by X-ray diffraction over the annealing temperature range from 674 to 1027K. The interdiffusivities have been determined from the decay rate of satellite peak intensity around (000). The temperature dependence of the interdiffusivities in Mo/Si and MoN/SiN multilayer films is expressed as D<@D4-@>D4(Mo/Si) = 2.0x10<@D1-16@>D1exp(-105 5 kJmol<@D1-1@>D1/RT) m<@D12@>D1s<@D1-1@>D1, D<@D4-@>D4(MoN/SiN) = 1.6x10<@D1-5@>D1exp(-351 88 kJmol<@D1-1@>D1/RT) m<@D12@>D1s<@D1-1@>D1.The large reduction in the modulation wavelength is observed in the annealed Mo/Si multilayer films. This behaviour is discussed in connection with the stuctural change. The superconducting transition temperature Tc and the upper critical field Hc<@D22@>D2 have been examined by resistance measurements. The 【.Ibdabar.】 dependence of Tc shows that the multilayer films with equal thichness of Mo and Si are superconducting with the maximum Tc, 6.1 K for 【.Ibdabar.】 =2.3 nm. The superconductivity of the multilayers has been confirmed to result from amorphous MoSi phase formed in the interfacial region of the sublayers. The thichness of the superconducting amorphous layer is estimated to be about 3 nm from the 【.Ibdabar.】 dependence of Tc and from the result of the anisotropy of Hc<@D22@>D2. Keeping the Mo sublayer thickness less than 2.4 nm to suppress the appearance of the crystalline Mo and increasing the Si sublayer thickness, an ideal quasi-two dimensional superconductor with with dHc<@D22@>D2 /dT as high as 180 kOe/K has been realized.

采用双射频磁控溅射技术制备了Mo/Si多层膜。X射线衍射仪表明，当调制波长小于3 nm时，Mo和Si亚层均为非晶态，而当调制波长大于3 nm时，Mo亚层中出现晶态体心立方结构。用X射线衍射法研究了Mo/Si和MoN/SiN多层膜在674-1027K温度范围内的互扩散。根据(000)附近卫星峰值强度的衰减率确定了互扩散系数。Mo/Si和MoN/SiN多层膜的互扩散系数与温度的关系为：D&lt；@D4-@&gt；D4(Mo/Si)=2.0x10&lt；@d1-16@&gt；D1exp(-105 5kJmol&lt；@d1-1@&gt；d1/rt)m&lt；@d12@&gt；d1s&lt；@d1-1@&gt；d1，D&lt；@d4-@@&gt；d4(MON/SIN)=1.6x10&lt；@d1-5@&gt；D1exp(-351 88kJmol&lt；@d1-1@&gt；d1/rt)m&lt；@d12@&gt；d1s&lt；@d1-1@&gt；d1。这一行为将结合结构变化进行讨论。通过电阻测量测量了超导转变温度T_c和上临界场Hc&lt；@D22@&gt；D2。T_c对[Ibdab.]的依赖关系表明，Mo和Si厚度相等的多层膜是超导薄膜，在[Ibdab.]=2.3 nm处有最大T_c，6.1K。多层膜的超导电性被证实是由于在亚层的界面区形成了非晶态的MoSi相。超导非晶层的厚度由T_c的[Ibdabar.]依赖关系和Hc&lt；@D22@&Gt；D2各向异性的结果估计约为3 nm。将Mo亚层厚度控制在2.4 nm以下，抑制了晶态Mo的出现，增加了Si亚层厚度，获得了dhc&lt；@d22@&gt；d2/dt高达180kOe/K的理想准二维超导体。