Thickness dependence of critical currents and depth profiling of transport properties in high rate in-situ grown YBa2Cu3O7-x films

摘要

YBa2Cu3O7-x (YBCO) films are grown by in-situ electron beam evaporation at high deposition rates (100～350 ?/sec). The YBCO films are found to consist of two regions as a function of thickness: a region on the bottom with defect-free microstructure reflecting layer-by-layer growth and at the top a defected type reflecting island-growth. We suggested a new phase stability to explain this growth behavior, with Ba-Cu-O liquid fluxes. The films show critical current density greater than 2 MA/cm2 on crystal substrates. Depth profiling of the transport properties (critical current density and resistivity) has been performed by etching the layers, elucidating that it is the island-growth layer where high critical current density is being carried.