Correlations between deposition parameters and structural and electrical properties of YBa2Cu3O7−δ thin films grown i n s i t u by sequential ion beam sputtering

Abstract

We have studied the correlations between deposition parameters and structural and electrical properties of YBa2Cu3O7−δ thin films grown in situ by sequential ion beam sputtering. Epitaxial, c-axis oriented YBa2Cu3O7−δ films were grown both on (100) SrTiO3 and on (100) MgO substrates following the stacking sequence of the ‘‘123’’ compound, with deposited layer thicknesses nominally equal to 1 monolayer. The c-axis lattice parameters obtained were larger than the corresponding lattice parameter in bulk samples, even after low-temperature anneals in O2. The transition temperatures were found to decrease with the enlargement of the c-axis lattice parameter. A clear correlation between growth temperature and the value of the c-axis lattice parameter was observed. The c-axis lattice parameter and the x-ray linewidth of Bragg reflections with the G vector along the c-axis were also found to be correlated. This suggests a relationship between the c-axis lattice parameter and the structural coherence of the epitaxial films.