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 YBa2Cu3O7-delta (YBCO) were grown on LaAlO3 substra tes, and the new possibilities arising from the excellent control over the laser spot parameters were explored. Films with high transition t emperatures (T-c approximate to 90 K, T-c approximate to 0.5 K) and sm ooth surfaces were obtained. It has been shown that target wear is gre atly reduced, resulting in significantly increased lifetime of the tar get and possibly reduced particle density on the films. (C) 1998 Elsev ier Science B.V.