Higher oxidization rate of photo-assisted annealing compared with thermal annealing after YBa2Cu3O7-delta films growth

Abstract In order to study the possible advantage of photo-assisted MOCVD compared with thermal MOCVD during the annealing process after film growth, a piece of c -axis oriented YBa 2 Cu 3 O 7 − δ film on Φ1″ LaAlO 3 (1 0 0) substrate was prepared by photo-assisted MOCVD. It has well in-plane alignment and high critical current density ( J c  > 2.5 MA/cm 2 , @ 0 T, 77 K, thickness ≈ 430 nm). Small pieces cut from it were annealed by photo-assisted or thermal annealing process to realize deoxidization or oxidization respectively. By monitoring the c -axis lattice constant, it was found that oxidization rate of photo-assisted annealing is obviously higher than that of thermal annealing. Inversely, the deoxidization rate of photo-assisted annealing is lower than that of thermal annealing. And a phenomenon that the long-time stable c -axis lattice constant is related to the temperature, unrelated to annealing process has been observed. It conforms to the thermodynamic equilibrium which is relative to annealing temperature and oxygen partial pressure, irrespective to whether photo activation or thermal activation.