Abstract
我們利用雷射濺渡法製作高溫超導薄膜與氧化物薄膜並有很好的成果, 我們也提出一種新的結構來製作雙外延磊晶超導晶界結, 由此可在釔鋇銅氧薄膜上形成百分之百45度角晶界, 讓在超導元件的製作上能得到更好的特性。另外我們也利用 X 光繞射與 TEM 的方法來研究氧化物薄膜與 MgO基材的介面結構, 此結果有助於我們研究氧化物薄膜磊晶成長的一些特性。In order to obtain 100% bi-epitaxial 45 degrees grain boundaryjunctions of YBCO, we have systematically examined the in-planeepitaxy of CeO2 films grown on MgO substrates. The inevitablepresence of CeO2[110]//MgO[100] causes mixtures of in-planerotation of 0 degree and 45 degrees between YBCO/CeO2/MgO andYBCO/MgO.We have further developed a new structure,namely YBCO/CeO2/YSZ/MgO and YBCO/MgO boundary, so that 100 % in-planerotation of 45 degrees can be routinely obtained. The model ofthe in-plane epitaxial relationship between the multi-layersusing near coincident site lattices (NCSL) was proposed. Thecritical current density of the junctions made on the boundaryis 3x10e3 A/cm2 at 77K, while the rest of the film has criticalcurrent density of 10e6 A/cm2. The current-voltagecharacteristics of the junctions show resistively shuntedjunction behavior. The better epitaxy of our new structure canlead to a better control of grain boundary critical currentdensity, which is the key technology to the SQUID fabrication.For the understanding of the interface between YSZ and MgO, weused the X-ray rod scan and transmission electron microscopy(TEM) to characterize the structure. The TEM image reveals theinterfacial separation directly, and the result is consistentwith the speculation from the X-ray rod scan analysis. Thersults give us a hint to study the epitaxial growth of oxidethhin films.