Pulsed laser deposition of YBCO thin films in a shadow mask configuration

We present an investigation on a modified pulsed laser deposition method (PLD) that employs plume geometric shadowing (Nd:YAG laser, 1.06 mu m, 2.5 J/cm(2). YBCO target). A plane shadow mask and a newly proposed helical mask were used. The aim of our approach was to improve the film surface morphology. The study investigated the influence of the main geometrical parameters of the two configurations on the plume propagation and film morphology. Using the shadow plane mask method we deposited extremely smooth YBCO films with a roughness of 4-5 nm (RMS), which is an improvement of two orders of magnitude compared with standard PLD. The helical shadow mask allows deposition of films of the same roughness as in the plane mask case, but brings further improvement by eliminating the film thickness non-uniformity, typical for plane mask configuration. In both cases the deposition rate decreased up to 7-12 times compared with standard PLD. (C) 2000 Elsevier Science S.A. All rights reserved.