Pulsed Laser Deposition of Dielectric and Ferroelectric Thin Films

Pulsed laser deposition is a good technique for rapidly prototyping thin films. A target material is congruently vaporized by the laser preserving the stoichiometry of the target in the laser generated plume.

The NIST Pulsed Laser Deposition (PLD) Facility consists of a multiported deposition chamber with an oil-free pumping system. The chamber contains a dual target assembly capable of rotating and translating the target so that the entire surface of the target is used during the deposition. A heater assembly holds the substrate in position and at the required temperature during the deposition. Metered background gas can be maintained in the chamber during the deposition. An excimer laser (KrF) operating at 248 nm is used as the ablating source. The laser beam enters the chamber through a beam delivery system that includes an adjustable focus lens, dual beam path, variable aperture, and variable attenuator.

In-situ diagnostics available include high speed multi-channel emission and adsorption spectroscopy, high speed imaging, and a deposition rate monitor. Examples of the high speed imaging of PLD films are viewable in the Ceramics Division's Gallery. Thin films produced in the NIST PLD Facility include, but are not limited to, high T_c superconductors, lead zirconate titanate, barium titanate, barium strontium titanate, alumina, zirconia, and silver/magnetite nanocomposites.

Extensive work has been done with barium titanate targets to characterize the PLD process. Films produced have been subjected to x-ray analysis, SEM, TEM, and AFM as well as compositional analysis. In addition, Spectroscopic Reflectometry has been used to map out the thickness of the films and determine their optical properties. Recently the pulsed laser deposition facility has been modified for dual target combinatorial library preparation.