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

TL;DR

This paper reports the growth of epitaxial MgB2 thick films with columnar structures on Al2O3 substrates using HPCVD, achieving high growth rates and promising superconducting properties for potential applications.

Contribution

It introduces a novel HPCVD method with a special susceptor to produce high-quality MgB2 films with unique columnar structures and high growth rates.

Findings

High growth rate of 0.17 um/min achieved

Superconducting transition temperature of 40.5 K

Critical current density of 1.5 x 10^6 A/cm^2 at 30 K

Abstract

Epitaxial MgB2 thick films were grown on Al2O3 substrates at 600 oC by using the hybrid physical chemical vapor deposition (HPCVD) technique. In order to obtain a high magnesium vapor pressure around the substrates, we used a special susceptor having a susceptor cap and achieved a very high growth rate of 0.17 um/min. Hexgonal-shaped columnar structures were observed by cross-sectional and planar view transmission electron microscope (TEM) images. For the 1.7-um-thick film, the Tc was observed to be 40.5 K with a Jc of 1.5 x 10^6 A/cm^2 at 30 K. The vortex pinning mechanism by intercolumnar boundaries will be discussed.