Adsorption Controlled Molecular Beam Epitaxy in the Barium Bismuth Oxide System
23 July 1989
The simple cubic perovskite structure of the potassium doped barium oxide superconductors makes this system a very attractive candidate for artificially structured superconducting materials. We have investigated molecular beam epitaxy in this system and have found that the stoichiometry of BaBiO sub 3 and related materials can be controlled by the adsorption of bismuth, just as MBE of III-V materials is controlled by the adsorption of group V elements. The bismuth sticking coefficient depends strongly on oxygen radical flux and on the substrate temperature. For substrate temperatures around 350C and high oxygen flux, the Ba/Bi ratio of the growing film is close to 1, as measured by Rutherford backscattering, with only weak dependence on the Ba/Bi flux ratio.