Correlations between deposition parameters and structural and electrical properties of YBaCuO thin films grown in situ by sequential ion beam sputtering

We have studied the correlations between deposition parameters and structural and electrical properties of YBaCuO thin films grown in situ by sequential ion beam sputtering. Epitaxial, c-axis oriented YBaCuO films were grown both on (100) SrTiO 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 O. 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.