Atomic layer by atomic layer growth of DyBaCuO superconducting thin films by molecular beam epitaxy

Superconducting thin films of DyBaCuO have been achieved by molecular beam epitaxy. The films are strongly oriented with the c axis perpendicular to the substrate, and currently reach R=0 between 70 and 80 K. Critical temperatures (R=0) up to 50 K were obtained on 150-Å-thick films deposited atomic layer by atomic layer. These films present a flat surface as observed by high-energy electron diffraction. We show that in this process, a nominal 1:2:3 composition is not sufficient for the obtention of flat superconducting film. A good accuracy in the number of atoms deposited for each atomic layer is required.