Growth of superconducting Bi₂Sr₂Ca_n-1Cu_nO_x thin films by atomically layered epitaxy

We have developed a technique for atomically layering crystallized films of Bi₂Sr₂Ca_n-1Cu_nO_x, in-situ, on SrTiO₃ substrates. These compounds have a layered structure along the c-axis of the unit cell. To grow c-axis oriented films, atomic monolayers of the constituent atoms were sequentially deposited on hot substrates by shuttering the fluxes from thermal effusion cells in such a way as to build up the crystal structure of the film. Carious stable and metastable phases were grown in this way, along with atomically precise superlattice structures. Oxidation of the films was accomplished during growth using a beam of ozone. The films were superconducting as grown, with complete resistive transitions as high as 86 K. Moreover, reflection high energy electron diffraction (RHEED) patterns observed during growth, as well as post growth analysis by X-ray diffraction (XRD) and high resolution scanning electron micrography indicate the films to be single crystal and heteroepitaxial.