PARTICULATE REDUCTION IN THE PULSED-LASER DEPOSITION OF BARIUM-TITANATE THIN-FILMS

A particulate-reduction approach has been developed, based on a pulsed supersonic gas-jet that selectively deflects particulates from the de position stream during pulsed laser deposition of BaTiO3 thin films. I n situ imaging, using an intensified CCD camera, has shown that the de sirable atomic, ionic, and molecular species move toward the substrate with velocities on the order of 10(6) cm s(-1), while the undesirable particulates move at velocities on the order of 10(4) cm s(-1) and sl ower. This separation of velocities is sufficient that the pulsed gas- jet can be timed to impact the particulates after the vapor species re ach the substrate, but while the particulates are still near the targe t, allowing for near-maximum deflection. Key parameters with this appr oach are the sharpness and the timing of the valve opening and closing . Initial results show that at least an order of magnitude reduction i n the number of film particulates is achieved. (C) 1998 Elsevier Scien ce B.V.