A Method to Fabricate Biaxially Textured MgO Buffer Layer for HTS Coated Conductor

In this paper, a radio-frequency magnetron sputtering system without any assisting ion source was employed to fabricate biaxially textured MgO films on the substrates of amorphous Y2O3/Al2O3/Hastelloy stacks. During the deposition process, the growing MgO film was bombarded by an off-normal energetic particle flux mainly composed of oxygen atoms and negative oxygen ions, which originated from the target surface. MgO obtained a biaxial texture due to such bombardment; thus, this method is named energetic particle self-assist deposition (EPSAD). The texture of EPSAD-MgO films was evaluated via the X-ray diffraction measurement of the postdeposited homoepitaxial MgO layers. An out-of-plane orientation of MgO (111) and a three-fold symmetric in-plane alignment were observed. The MgO texture was optimal when the EPSAD-MgO thickness was about 10 nm. The formation of biaxial texture during the EPSAD process was verified by a control study, and the influences of target-inclined angle and target-substrate distance were also investigated. Furthermore, the mechanism of the EPSAD-MgO method was compared with those of the inclined substrate deposition and ion beam assisted deposition. This study proposed a new method to fabricate a biaxially textured MgO buffer layer for high temperature superconducting (HTS) coated conductors. More optimization research will be conducted in our future study.