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研究了MgO基片在高温退火时表面形貌和表面结构的变化,以及它对CeO2缓冲层和Tl-2212超导薄膜生长的影响。原子力显微镜(AFM)研究表明,在流动氧环境中1100℃温度下退火,MgO的表面首先由未退火时的皱褶形貌,演化为光滑表面,随着退火时间的延长,表面形貌最终演化为具有光滑基底的独立生长峰结构。XRD测试表明,通过高温热处理可以大幅度提高MgO基片表面结晶的完整性。在1100℃温度下热处理8小时的MgO基片上可以生长出具有高度c轴取向的CeO2(001)缓冲层。然后在此缓冲层上制备了厚度为500nm的外延Tl-2212超导薄膜,其临界转变温度(Tc)达到108.6K,液氮温度下临界电流密度(Jc)为2.8mA/cm2,微波表面电阻Rs(77K,10GHz)约为360.9μΩ。
The change of surface morphology and surface structure of MgO substrate at high temperature and the effect of MgO on the growth of CeO2 buffer layer and Tl-2212 superconducting thin films were investigated. Atomic force microscopy (AFM) studies show that, in a flowing oxygen environment at 1100 ℃ annealing temperature, the surface of MgO first unwired wrinkle morphology, evolved into a smooth surface, with the annealing time, the surface morphology of the final evolution An independent growth peak structure with a smooth substrate. The XRD test shows that the surface crystallinity of MgO substrate can be greatly improved by high temperature heat treatment. A CeO2 (001) buffer layer with a high degree of c-axis orientation can be grown on a MgO substrate heat-treated at 1100 ° C for 8 hours. Then, an epitaxial Tl-2212 superconducting thin film with a thickness of 500nm was prepared on this buffer layer with a critical transition temperature (Tc) of 108.6K, a critical current density (Jc) of 2.8mA / cm2 at a liquid nitrogen temperature, a microwave surface resistance Rs (77K, 10GHz) is about 360.9μΩ.