Thin film synthesis with ultrafast lasers

Application of ultrafast lasers to materials synthesis and processing is rapidly developing in directions of industrial relevance. Before full value can be extracted from such technology however, an operational understanding of their advantages and disadvantages needs to occur. Important issues regarding such applications are discussed in this paper in relation to fundamental aspects of energy absorption, lattice response, threshold damage production, and ablation plume development. These phenomena relate to the practical use of ultrafast lasers in micromachining and thin film deposition and reflect the physical differences to be found between long pulse and short pulse effects in materials. Understanding of these physical processes is enhanced through the use of practical computer models for the electronic and thermodynamic response of a material and the hydrodynamic and electrodynamic expansion of ablation plumes in terms of ion species and energies. Preliminary results on thin film deposition of boron nitride as a function of substrate temperature and ablation ionics is presented as an example of the unique possibilities provided by ultrafast lasers in the area of thin film synthesis and growth processing. Films are analyzed by spectroscopic ellipsometry for optical properties, ion beam analysis for stoichiometry, infrared absorption for structural properties, and atomic force microscopy for surface properties.