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 deposition stream during pulsed laser deposition of BaTiO3 thin films. In situ imaging, using an intensified CCD camera, has shown that the desirable atomic, ionic, and molecular species move toward the substrate with velocities on the order of 106 cm sy1, while the undesirable particulates move at velocities on the order of 104 cm sy1 and slower. This separation of velocities is sufficient that the pulsed gas-jet can be timed to impact the particulates after the vapor species reach the substrate, but while the particulates are still near the target, allowing for near-maximum deflection. Key parameters with this approach are the sharpness and the timing of the valve opening and closing. Initial results show that at least an order of magnitude reduction in the number of film particulates is achieved. q1998 Elsevier Science B.V.