Large-area pulsed laser deposition of YBCO thin films: homogeneity and surface

YBCO thin films and buffer layers are deposited by a special PLD setup with an 8-cm line focus on cylindrical targets and substrate scanning perpendic ular to it. Different kinds of substrates (SrTiO3, MgO, LaAlO3, Y-ZrO2 and sapphire) as large as 7 x 20cm(2) were coated with YBCO. Two important aspe cts of the presented PLD setup will be discussed in detail: the method of s ubstrate heating and the variation of the angle between the incident laser beam and the target surface ("wobbling"). The surface of the target materia l has been investigated by SEM. The influence: of target "wobbling" on the time stability of the plasma will be discussed. The homogeneity of the depo sited YBCO films with respect to structural and electrical properties has b een investigated by XRD, RBS/channeling, and spatially resolved inductive m easurements of T-c and j(c). The values of j(c) on 7 x 20cm(2) in situ buff ered sapphire substrates are 2.0 MA/cm(2) at (77 K, 0 T) with a j(c) variat ion of less than +/-20%.