Oxygen diffusion in off-c-axis normal-state Bi2Sr2CaCu2O8+δ films

The anisotropy of the oxygen diffusion in the high-T-c-superconductor Bi2Sr2CaCu2O8+delta was investigated using off-c-axis prepared thin films. High-quality oriented films with thickness 1000 Angstrom and c-axis inclined by a tilt angle a with respect to the normal of the film surface were grown up to alpha = 15 degrees. Oxygen diffusion following a small change of the ambient oxygen partial pressure in the temperature range 200-400 degrees C was monitored by in situ resistance measurements. Diffusion times according to an activated process tau(-1) = tau(0)(-1) exp[-E/k(B)T] were found, with E = 0.6 eV and tau(0) = tau(0)(alpha) Becoming smaller with increasing tilt angle. A comparison of the experimental tau(0)(alpha) with a calculation of tau(0) for an ideal monocrystalline film suggests that as-grown films consist of crystalline grains with lateral dimensions similar to 1 mu m.