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Dresden 2014 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 12: High- and low-k-dielectrics (Joint Session with DF)

DS 12.2: Vortrag

Dienstag, 1. April 2014, 10:50–11:10, GER 37

Barium silicate (Ba2SiO4) as high-k dielectric material — •Shariful Islam1, Karl Hofmann2, and Herbert Pfnür11Institut für Festkörperphysik (ATMOS), leibniz universität hannover — 2Inst. f. Bauelemente der Mikroelektronik, leibniz universität hannover

In search of an alternative gate oxide, the structural and electronic properties of mixed Ba/Sr silicates on Si(001) were investigated. In order to specify the stoichiometry and band gap of these oxides we used X-ray Photoelectron Spectroscopy (XPS) and Electron Energy Loss Spectroscopy (EELS) respectively. Crystal structures were investigated by Spot Profile Analysis-Low Energy Electron Diffraction (SPA-LEED). Electrical characterization was done by CV and IV measurements.

Characteristics of high-k dielectric (Ba0.8Sr0.2)2SiO4 and Ba2SiO4 were studied both on structured and unstructured samples. Both oxides are stable at high temperature and at ambient atmosphere. Crystalline (Ba0.8Sr0.2)2SiO4 has dielectric constant, ε = 18 ± 2. The band gap was found to be 6.0 eV, with band offsets > 2eV both for valence and conduction band. The thick crystalline layers of pure (Ba0.8Sr0.2)2SiO4 were also grown. An ε = 19.6 ± 0.4, a small reduction of bandgap to 5.7 ± 0.1 eV and band offsets comparable to (Ba0.8Sr0.2)2SiO4 were found. Due to our growth procedure (diffusion of Si into oxide) leakage currents are still comparatively high (0.1 A/cm2 at 1V). Further electrical and structural properties of Ba2SiO4 will also be presented.

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