Controlled Growth of Superconducting Oxide Films Using Pulsed Laser Deposition

Abstract

ABSTRACT:Reflection high-energy electron diffraction (RHEED) has been used to monitor the homoepitaxial growth of SrTiO3 buffer layer, and subsequent heteroepitaxial growth of YBa2CU3O7-δ (YBCO) films, on (100) SrTiO3 by pulsed laser deposition (PLD). The RHEED pattern during initial growth of SrTiO3 becomes sharper and increases in intensity, suggesting that the smoothness of the substrate is improved by growth of the buffer layer. On the smooth surface, the growth of SrTiO3 occurs in a layer-by-layer mode as indicated by the intensity oscillations of the specular beam. YBCO films have been subsequently grown on the buffer layer using a combination of pulsed molecular oxygen and a continuous source of atomic oxygen, with the average background pressure maintained as low as 1 mTorr. A sharp streaky pattern, and intensity oscillations are also observed during growth of YBCO. The YBCO films after cooling down in 1 atm of O2 are superconducting, with zero-resistance temperature of 80 K.