Reducing delamination in MgB2 films deposited on Hastelloy tapes by applying SiC buffer layers

MgB2 is a promising candidate for superconductivity applications because of its metallic nature and its simple structure compared to other oxide superconductors. We have deposited MgB2 thin films on the SiC buffered-Hastelloy substrates by a hybrid physical-chemical vapor deposition (HPCVD) method. SiC buffer layers of varying thicknesses were grown on the Hastelloy substrates by a pulsed laser deposition (PLD) technique. As the SiC buffer layers thicken, the grain size of MgB2 films is distinctly decreased and the grains become much denser. MgB2 film deposited on bare Hastelloy shows a sign of partial delamination at the interface. Interestingly, the delamination was considerably reduced when the SiC buffer layers with the thickness of 170 and 250 nm were added into the MgB2 tape. This suggests that SiC buffer layers acted as an effective sticking agent, providing stronger adhesion to the MgB2-Hastelloy interface, hence the reduced delamination.