Low-temperature annealing effect of as-grown Bi-Sr-Ca-Cu-O thin films on superconducting property and the c-axis lattice constant

As-grown crystallized Bi2Sr2Ca1Cu2Ox phase films were prepared on MgO(100) substrates by rf magnetron sputtering. The as-grown film showed the Tc onset of 92 K and the Tc end of 82 K. By annealing in the furnace at 480 degree C after deposition, superconducting property and the c-axis lattice constant varied with atmosphere during annealing. The film after annealing in air at 480 degree C exhibited the highest superconducting transition with the Tc onset of 93 K and the Tc end of 85 K. The Tc onset increased when the c-axis lattice constant was increased, suggesting that the Tc onset increases with decreasing the oxygen content of the film