Influence of Seed Layer Materials on the Texture of IBAD-MgO Layer

Recently, the solution deposition planarization (SDP) technique for deposition of oxide layer for the IBAD-MgO template has attracted more attentions. Although the texturing mechanism of IBAD-MgO is still under debate, it is accepted that the seed-layer (the one close to the MgO) should fulfill several requirements, such as atomic flatness surface as well as material composition. In this work, in order to clarify the influence of SDP-seed layer materials on the texture of IBAD-MgO layer, we chose Gd–Zr–O, Gd₂O₃, ZrO₂, and Y ₂O₃ as seed layer materials. Atomic force microscopy (AFM), X-ray diffractometer (XRD), and reflection high energy electron diffraction (RHEED) were used to illustrate the correlation between the microstructure of the seed layer and the texture of IBAD-MgO film. AFM analysis shows that the atomic flatness was achieved on all the SDP films, as evidenced by the RMS value of around 0.3 nm on the 1 × 1 μm² grid area. RHEED results show that the poor texture of IBAD-MgO is present when using Gd₂O₃ and ZrO ₂ as seed layer. Like Y₂O₃, the SDP-GZO film as a seed layer exhibits good compatibility with IBAD-MgO. In addition, the XRD result on Gd–Zr–O xerogel powder implies that the films mainly consist of nanocrystalline Gd₂Zr₂O₇, which is a crucial feature of an efficient barrier layer. Eventually, a J_c value of 1.65 MA·cm⁻² (at 77 K, s.f.) was achieved on a full stack of YBCO/CeO₂/IBAD-MgO/SDP-layer/C276 sample.