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

采用双射频磁控溅射技术制备了多层Mo/Si薄膜。x射线衍射分析表明，对于调制波长，短于3nm的Mo和Si亚层都是无定形的；> 3 nm时，Mo亚层出现结晶体结构。在674 ~ 1027K的退火温度范围内，用x射线衍射研究了Mo/Si和MoN/SiN多层薄膜的相互扩散。通过（000）左右卫星峰强度的衰减率确定了扩散系数。Mo/Si和MoN/SiN多层膜中互扩散系数的温度依赖性表示为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。在退火的Mo/Si多层膜中观察到调制波长的大幅度减小。这种行为将与结构变化联系起来讨论。用电阻测量法测定了超导转变温度Tc和上临界场Hc<@D22@>D2。伊卜达巴。等厚度Mo和Si的多层膜具有超导性，最大Tc为6.1 K。】=2.3 nm。多层材料的超导性是由亚层界面形成的非晶MoSi相引起的。估计超导非晶层的厚度约为3nm。从Hc<@D22@>D2各向异性的结果。保持Mo亚层厚度小于2.4 nm，抑制Mo结晶的出现，增加Si亚层厚度，实现了dHc<@D22@>D2 /dT高达180 kOe/K的理想准二维超导体。

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.