Optimization of MOCVD Hardware Configuration and Process for Growth of High Quality (Gd,Y)BCO Superconducting Tapes Based on CFD Modeling

摘要

A systematic computational fluid dynamic (CFD) study was performed to investigate the effects of hardware configuration and process parameters on flow field and temperature profile above the film growth surface for (Gd,Y)BCO superconducting tapes in a metalorganic chemical vapor deposition (MOCVD) reactor. Significant improvement in the uniformity of flow field and temperature profile was achieved by optimizing the gap between showerhead and susceptor, showerhead length, gas flow rate, and chamber pressure. As results of the improvement in hardware configuration based on CFD modeling, high quality (Gd,Y)BCO superconducting films were achieved and the limit on growth rate was increased. The improvement was not only in the surface morphology (achieving more clean and smooth surface with less outgrowth grains and impurity phase particles), but also in the cross sectional microstructure view (more uniform from the bottom to the top) for thick films processed by the reel-to-reel MOCVD. A 1.76-mu m-thick (Gd,Y)BCO film in a 284-m-long tape yielded a self-field critical current of 769 A/12 mm width at 77 K.