Ln dependence in Ln(2)CuO(4) buffer layers of c-axis in-plane aligned a-axis oriented YBa2Cu3O7-delta thin film growth

Lanthanide (Ln) atom in Ln(2)CuO(4) buffer layer dependence of c-axis in-pl ane aligned a-axis oriented YBa2Cu3O7-delta (YBCO) thin film growth is disc ussed and preferred orientation growth model of a bc-plane matched growth m odel is proposed. The c-axis in-plane aligned a-axis oriented YBCO thin fil ms are very attractive from both the researches on the origin of high T-c. superconductors and microelectronics device applications. However the c-axi s in-plane aligned a-axis oriented films are difficult to grow. We have bee n proposing Ln(2)CuO(4) buffer layers for the c-axis in-plane aligned a-axi s oriented YBCO thin fdm growth. We have examined various Ln atoms in Ln(2) CuO(4) buffer layers for the growth of YBCO thin films by pulsed laser depo sition. From a lattice matching point of view, a Tb2CuO4 buffer layer is th e best one for the c-axis in-plane aligned a-axis oriented YBCO thin films. However the result shows that the Nd2CuO4 and Tb2CuO4 buffer layer causes YBCO thin films with c-axis oriented portion about 35% and 32%, by X-ray di ffraction peaks, which is much larger than those on Gd2CuO4 buffer layers ( 7.4%). The most promising Ln atom in Ln(2)CuO(4) buffer layers for the grow th of the c-axis in-plane aligned a-axis oriented YBCO thin films so far is Gd2CuO4 buffer layers or Eu2CuO4 buffer layers. (C) 2001 Elsevier Science B.V. All rights reserved.