Confined-Plume Chemical Deposition of Transition Metal Borides and Chalcogenides Initiated by Pulsed, Infrared, Tabletop Lasers
Beam, Jeremiah Cooper
Developing plasma-mediated methods to achieve local control of materials deposition at moderate temperatures is a topic of current interest. We report a novel method of obtaining crystalline coatings on soft substrates, advancing fabrication of energy-related functional materials, such as photovoltaic devices. Confined-plume chemical deposition (CPCD) occurs when pulsed laser irradiation initiates decomposition of chemical precursors with formation of a reaction plume (T roughly equal to 3000 K) under spatial and temporal confinement, resulting in nucleated growth or deposition of microcrystalline thin-film coatings. Temporal confinement of laser pulses allows residual heat to dissipate throughout the substrate material, minimizing collateral thermal damage. This process has been demonstrated using both visible (Nd:YLF, 527-nm) and infrared (Ti:Sapphire, 800-nm; Er:YAG, 2.94-µm) tabletop lasers as the irradiation source. Formation of ceramic (ReB2, MnB2), semiconductor (CdS), or piezoelectric (ZnO) microcrystalline coatings on polymer and biological substrates will be presented. Characterization methods include powder x-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectral (EDS), and Raman spectroscopy (where appropriate), and evaluation of the adhesion between ReB2/polymer samples.