Bi₂Sr₂Ca₁Cu₂Ox Thin Film Deposition by Q-switched YAG Laser

Abstract

The fourth harmonics of Q-switched YAG was used to deposit Bi₂Sr₂Ca₁Cu₂O_x (Bi-2212) films on MgO [100] substrates. A secondary function generator was employed to modulate Q-switch while the primary generator was synchronized with flash lamps to decrease the repetition rate of laser beam. At the rate of 2 Hz, the beam energy increased 50% per pulse and the fluctuation of power stayed in ±2% during the deposition. In order to decrease the number of particles on film, targets were irradiated by the laser before deposition. Using the fourth harmonics of slower Q-switch YAG, epitaxial growth of Bi-2212 was achieved on MgO [100] substrate with the transition temperature of 72 K. Comparing the results with those deposited using an excimer laser, higher oxygen pressure was required to obtain epitaxial growth of Bi-2212.