  We investigate the epitaxial growth of bilayer cuprate La2CaCu2O6+\delta
using pure ozone as an oxidant, and find that even the crystal with parent
composition without cation substitution can show metallic behavior with the aid
of epitaxial strain effect. The hole concentration is controlled simply by
excess-oxygen doping, and the films grown under the optimum conditions exhibit
superconductivity below 30 K. This is the first result on the superconductivity
of bilayer La2CaCu2O6+\delta induced purely by the excess oxygen.
