| Budget Amount *help |
¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1987: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1986: ¥800,000 (Direct Cost: ¥800,000)
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| Research Abstract |
The aim of this study is preparation and structure analysis of superconducting epitaxial films, which were made by means of various techniques; electron beam evaporation method, radio frequency (RF) sputtering method and ion beam sputtering method. Superconducting materials used were TaC, NbC, Nb_3Sn, Nb_3(Ge,Si) and YBa_2Cu_3Ox. The structures of those films were analyzed by high resolution electron microscopy and reflection electron diffraction patterns. The results are described as follow.
1. TaC and NbC thin films were made by electron beam evaporation technique.
Both epitaxial films were obtained on a substrate MgO at the temperature of about 400 ゜C. The orientation relations are TaC(001)[010]// MgO(001)[110] and NbC(001)[010]// MgO(001)[010].
2. Films of Nb_3Sn and Nb_3(Ge,Si) made by RF sputtering method did not grow epitaxially but consisted of fine crystallites. In this method, amorphous substrate is preferable. Nb_3(Ge,Si) epitaxial films were obtained by means of ion beam sputtering method, in which a substrate MgO at 600 ゜C was used. When films made by any sputtering method are thin, the structure is amorphous. When films become thick, crystallization is promoted.
3. Preparation of thin films of YBsa_2Cu_3Ox superconductor, which has the critical temperature above liquid nitrogen temperature, was tried. However the preparation condition of those films is very strict because oxygen atoms in the material are subject to remove in the vacuum duting heat treatment. There fore epitaxial films were not yet obtained in the present time.
4. Althogh we are examining the properties of superconducting thin films such as resistivity, transition temperature, density and mobility of carriers, we have not yet sufficient data. These remain as the future problems.
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