GROWTH OF YBA2CU3O7-DELTA IN PURE OZONE IRRADIATED WITH ULTRAVIOLET-LIGHT

Pure ozone has been successfully used as the source of reactive oxygen for in situ molecular beam epitaxy (MBE) growth of cuprate superconductor thin films. The thermally driven ozone-oxidation process is relatively inefficient, however, requiring high ozone partial pressures and leading in some cases to film nonuniformities. We show that pure ozone-oxidation during film deposition can be significantly enhanced by the additional use of ultraviolet (UV) irradiation. The UV energy produces excited-state O and O2 species from ozone via a chain-type mechanism, thereby increasing the ozone activity at least tenfold. In comparison to the film growth process relying solely on thermal ozone decomposition, it is possible to lower the ozone pressure by an order of magnitude while improving the quality of the superconducting films.