Thickness dependence of grain growth orientation in MgB2films fabricated by hybrid physical-chemical vapor deposition

Abstract

We have investigated the effect of thickness of the MgB2 film on the grain growth direction as well as on their superconducting properties. films of various thicknesses were fabricated on c-cut substrates at a temperature of by using hybrid physical-chemical vapor deposition (HPCVD) technique. The superconducting transition temperature () was found to increase with increase in the thickness of the film. X-ray diffraction analysis revealed that the orientation of grains changed from c-axis to a-axis upon increasing the thickness of the film from 0.6 to 2.0 . grains of various orientations were observed in the microstructures of the films examined by scanning electron microscopy. It is observed that at high magnetic fields the 2.0--thick film exhibit considerably larger critical current density () as compared to 0.6--thick film. The results are discussed in terms of an intrinsic-pinning in similarly as intrinsic-pinning occurring in high-Tc cuprate superconductors with layered structure.