Physical Characterization of Ferroelectric Thin Films

Electronics

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Mg-doped Ba0.8Sr0.2Mg0.1Ti0.9O3 (BST) thin film structural and physical characterization results are presented. The (Ba,Sr)TiO3 ceramic targets have been prepared by selfpropagating high-temperature synthesis method and a nano-film is fabricated by the pulsed laser deposition method. Ferroelectric films have been physically characterized (thickness, surface morphology, composition) by means of ellipsometry, scanning-electron microscopy, Rutherford backscattering spectrometry (RBS) and atomic force microscopy (AFM) methods. The results of ellipsometric investigation of the Mg-doped Ba0.8Sr0.2Mg0.1Ti0.9O3 thin film and the comparison of Mg-doped Ba0.8Sr0.2Mg0.1Ti0.9O3 targets prepared by the SHS technology show that BST thin films behave differently than bulk BST. It is observed that the dielectric constant decreases with a decrease in the thickness of the BST thin film. The thickness dependence of the dielectric constant varies with the substrate temperature and the grain size effect. The thickness dependence of dielectric permittivity is explained in Schottky barrier model. The RBS investigations of the examined BST films confirm a stoichiometric growth and an excellent crystalline quality and confirm a stoichiometric good growth. The measured root mean square (rms) roughness is about 7,6 nm. The micrographs show a closed BST thin film without micro-cracks or pores. The BST surface possesses a grainy texture with a typical grain size of ~50 nm.