Laser irradiation effects in YBa2Cu3O7 amorphous films

The effect of laser irradiation on coupling energy of O and Cu atoms in YBa 2Cu3O7 thin films was investigated by measuring the changes in structure, o ptical transmittivity and conductivity of irradiated films. Photon energies of h omega = 2.44 eV, h omega = 2.15 eV (Cu vapor green laser) and ho = 5. 01 eV (KrF excimer laser) were used for film irradiation. Irradiation by lo wer photon energies enhanced the growth of the dielectric phase by destroyi ng the metallic clusters. With charge transfer gap Eg=1.75 eV for O-2P doub le right arrow Cu-3d transition in the insulator, the photon energy in this case is sufficient to generate a bounded exciton. By contrast, UV irradiat ion influences mainly the clusters with metallic conductivity.