Analysis of Temperature Dependence of Phases and Surface Morphology of Bi2Sr2Cax−1CuxOy Thin Films Using Reactive Co-Deposition Method

A reactive co-deposition processing for obtaining high-quality single-phase Bi2Sr2Cax−1CuxOy (Bi2212) thin films has been investigated using molecular beam epitaxy (MBE) with 2.7 × 10−3Pa ozone gas introduction for oxidation. The thin films with a constant composition of almost 2:2:1:2 were designed to be fabricated at the substrate temperature between 675 and 780°C, the substrate temperature dependence of the surface morphology and the emergence phases were investigated in detail. A noticeable result is that the distribution of Cu element in the thin films is sensitively changed with the substrate temperature. At 750°C it is inclined to locate in the periphery of each grain through the diffusion process. At 780°C the Cu-compositional fluctuation brought around the dendritic crystal growth in the thin films. Below 705°C, the Bi2212 single-phase cannot be achieved in the thin films.