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The photoconductivity spectra of semimagnetic semiconductor Cd0.7Mn0.3Se have been measured at 50-300 K and in the wavelength range of 5500? to 8000?. It is found that the energy gap of Cd0.7Mn0.3Se changes with the temperature linearly, and the temperature coefficient (dEg/dT) is about -7×10-4 eV/K. A photoconductivity peak which is related to Mn2+ is also found. This peak is located around 1.85 eV, nearly unshifted with variation of the temperature. The possible transition mechanisms in Cd1-xMnxSe have been discussed in the light of group theory and crystal field theory, and the results are in good agreement with experiments. 相似文献
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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
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高T_c的Y-Ba-Cu-O超导材料在弱电方面进入实用的一个重要条件,就是需要制备出优质的超导薄膜。已有多种制备超导薄膜的方法见报道。用蓝宝石或Si衬底制备超导薄膜,通常会由于薄膜与衬底强烈的界面反应使其零电阻温度大为降低,严重时甚至变成非超导。而我们在实验中发现,YSZ(掺钇稳定立方氧化锆)衬底在高温下与薄膜的界面反应也较为严重。在YSZ衬底上沉积一层Ag缓冲层则可以减轻薄膜与村底的相互作用。 相似文献
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本报导了延时为2.2ns的TC超导薄膜延迟线的制作工艺。应用直流磁控溅射在10×10mm^2LaAlO3衬底上均匀地外延生长450nm优质YBCO超导薄膜,采用离子束干法刻蚀技术制作出宽为166μm长为174mm的曲折线图形,配以合适的气密性封装,经美国HP8507矢量网络分析仪测量,在温度78K频率1.2GHz时,延迟线的插入损耗低达0.04dB,仅为相同条件下铜膜延一插损的1/160。 相似文献
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从实验中观察到,低能离子轰击后的铌酸锂晶体表面层在3500—6500?之间出现至少两个光吸收峰,表面的相对暗电导率增加两个数量级。这表明离子轰击后的铌酸锂中产生了附加的光吸收和电导激活中心。在离子轰击过程中,由于某些原子基团和原子的优先溅射,在表面层中造成相当大的化学计量比偏离,它直接影响晶体的光学和电学性质。XPS(X射线电子能谱)测试结果证实,这一表面层的构成符合铌酸锂缺陷结构的空位模型。讨论了附加激活中心的成因,并据此解释了Ar+/O+混合离子轰击铌酸锂晶体所得到的结果。
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半熔融烧结靶直流磁控溅射外延生长YBCO超导薄膜 总被引:1,自引:1,他引:0
直流磁控溅射使用半熔融大直径平面烧结靶,在(100)SrTiO_3衬底上原位生长 YBa_2Cu_3·O_(7-δ)超导薄膜,可以很方便地和重复地获得临界电流密度高(J_c=3.4×10~6A/cm~2在77KB=0时)、微波表面电阻 R_s 较低(在77K,50.9GHz 时,R_s≤37mΩ)和均匀区较大的超导薄膜.X 光衍射,X 光双晶衍射摇摆曲线测量和透射电子显微镜分析结果表明,所得的 YBCO 薄膜为高度 c 取向的单晶外延膜. 相似文献
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