Tunable stoichiometry of SiO x - BaTiO y - BO z fabricated by multitarget pulsed laser deposition

Abstract

Downloaded From: http://nanophotonics.spiedigitallibrary.org/ on 08/22/2015 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspxAbstract. Oxide materials of desired stoichiometry are challenging to make in small quantities. Nanostructured thin films of multiple oxide materials were obtained by using pulsed laser deposition and multiple independent targets consisting of Si, BaTiO 3 , and B. Programmable stoichiometry of nanostructured thin films was achieved by synchronizing a 248-nm krypton fluoride excimer laser at an energy of 300 mJ∕pulse, a galvanometer mirror system, and the three independent target materials with a background pressure of oxygen. Island growth occurred on a per pulse basis; some 500 pulses are required to deposit 1 nm of material. The number of pulses on each target was programmed with a high degree of precision. Trends in material properties were systematically identified by varying the stoichiometry of multiple nanostructured thin films and comparing the resulting properties measured using in situ spectroscopic ellipsometry, capacitance measurements including relative permittivity and loss, and energy dispersive spectroscopy (EDS). Films were deposited ∼150 to 907 nm thickness, and in situ ellipsometry data were modeled to calculate thickness n and k. A representative atomic force microscopy measurement was also collected. EDS, ellipsometry, and capacitance measurements were all performed on each of the samples, with one sample having a calculated permittivity greater than 20,000 at 1 kHz.

Effects of Plume Hydrodynamics and Oxidation on the Composition of a Condensing Laser-Induced Plasma

“…11 However, the ambient gas composition and pressure, laser parameters, and target composition can induce molecular formation in the expanding laser-induced plasma plume, which can change the resultant stoichiometry. 7,12,13 Numerous studies have used time-resolved emission spectroscopy to study the formation of molecules in laser ablation plumes, 14−17 and some have begun to explore the spatial distribution of such molecules. 18−20 Some studies have compared atomic and molecular emission features using narrow bandpass filters to analyze plume hydrodynamics and composition, 18,19 while others have investigated diatomic oxide formation via laser-induced fluorescence (LIF) as a function of spatial position.…”

“…Pulsed laser deposition typically imparts near-stoichiometric transfer of material, making it an ideal method for thin film deposition . However, the ambient gas composition and pressure, laser parameters, and target composition can induce molecular formation in the expanding laser-induced plasma plume, which can change the resultant stoichiometry. ,, …”