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Please use this identifier to cite or link to this item: http://hdl.handle.net/1860/3298

Title: Use of spectroscopic ellipsometry and modeling in determining composition and thickness of barium strontium titanate thin films
Authors: Bruzzese, Dominic G.
Keywords: Materials engineering;Thin films;Ellipsometry
Issue Date: 8-Jul-2010
Abstract: Significant advances have been made in the understanding of ferroelectrics since they were first observed in Rochelle salt by Valasek, in 1920 [1]. Recently investigated effects of improved properties by compositionally grading ferroelectrics has sparked new and growing interest in the materials as electric field tunable dielectric materials. With this increased interest in devices made from these materials comes the increased demand to effectively synthesize and characterize these films in low cost high volume production. This work attempts to bring the technique of variable angle spectroscopic ellipsometry (VASE) and computer modeling to the field for answering this need of an all-in-one, rapid characterization tool. To achieve this goal, metallorganic solution deposited Ba[x]Sr[1-x]TiO[3] (BST) thin films on silicon and platinized silicon substrates were characterized by several well-known techniques to fully understand the structure, morphology, layer thickness, and topographical roughness. With the information gained, a physical representation of the material system was constructed for the use of modeling the layer thickness and optical constants of the BST layer. VASE was then used to provide all of the information needed, the ellipsometric parameters as a function of energy and incident angle, to calculate layer thickness and optical constants. The next step was to correlate the optical constants, represented by an optical dielectric function parameterization, with the layer's barium to strontium ratio or composition. This connection was made by the dependence of the bandgap on composition. As a result of this work, a step-by-step method was developed which, by use of only VASE, can identify layer thickness and composition of an unknown sample. The caveat is the film must have been produced by the MOSD technique, and have been deposited on either silicon or platinized silicon. This study is extendable to other deposition techniques and substrates. Work supported by the Army Research Once under W911NF-08-C-0124 and W911NF-08-1-0067. C.L.S acknowledges support from the NSF under CMMI-0804543.
URI: http://hdl.handle.net/1860/3298
Appears in Collections:Drexel Theses and Dissertations

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