Growth of Epitaxial MgB2 Thick Films with Columnar Structures by Using HPCVD

摘要

Epitaxial MgB2 thick films were grown on Al2O3 substrates at 600 oC by usingthe hybrid physical chemical vapor deposition (HPCVD) technique. In order toobtain a high magnesium vapor pressure around the substrates, we used a specialsusceptor having a susceptor cap and achieved a very high growth rate of 0.17um/min. Hexgonal-shaped columnar structures were observed by cross-sectionaland planar view transmission electron microscope (TEM) images. For the1.7-um-thick film, the Tc was observed to be 40.5 K with a Jc of 1.5 x 10^6A/cm^2 at 30 K. The vortex pinning mechanism by intercolumnar boundaries willbe discussed.