Epitaxial HTS thin films grown by PLD with a beam homogenizer

A beam homogenizer has been used in combination with a standard pulsed laser deposition PLD.system. This combination reproducibly resulted in laser spots of precisely predetermined shapes and energy densities, thus providing control over one of the most difficult parameters in PLD. Thin films of YBa2Cu3O7yd YBCO.were grown on LaAlO3 substrates, and the new possibilities arising from the excellent control over the laser spot parameters were explored. Films with high transition temperatures Tcf90 K, Tcf0.5 K.and smooth surfaces were obtained. It has been shown that target wear is greatly reduced, resulting in significantly increased lifetime of the target and possibly reduced particle density on the films. q1998 Elsevier Science B.V.