In   situ layer-by-layer growth of YBa2Cu3O7− x thin films by multitarget sputter deposition

• Published in: Applied physics letters 1992-12, Vol.61 (23), p.2826-2828
• Main Authors: Yang, K-Y., Dilorio, M. S., Yoshizumi, S., Maung, M. A., Zhang, J., Tsai, P. K., Maple, M. B.
• Format: Article
• Language: English
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.108050

We have fabricated YBa2Cu3O7−x thin films using in situ layer-by-layer sputter deposition from metal targets. Yttrium, barium, and copper metals were deposited in the atomic monolayer sequence to construct the perovskite structure in the [001] direction. X-ray diffraction indicates that these films are c-axis oriented with the [001] direction normal to the film surface. Smooth films with zero-resistance transition temperature Tc0=80 K and critical current density Jc(4.2 K)∼2×107 A/cm2, measured in zero magnetic field, have been grown on LaAlO3(100) substrates. Under the conditions studied, all films have a suppressed Tc and an expanded c-axis lattice constant, with the degree of Tc suppression inversely proportional to the lattice constant. Tc and surface morphology were shown to be sensitive to the fractional monolayer coverage φ during each layer’s deposition. The results suggest that films grow in the layer-by-layer mode as opposed to island growth.