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DF: Fachverband Dielektrische Festkörper

DF 6: High- and low-k-dielectrics (Joint Session with DS)

DF 6.2: 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 Pfnür¹ — ¹Institut 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 (Ba_0.8Sr_0.2)₂SiO₄ and Ba₂SiO₄ were studied both on structured and unstructured samples. Both oxides are stable at high temperature and at ambient atmosphere. Crystalline (Ba_0.8Sr_0.2)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 (Ba_0.8Sr_0.2)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 (Ba_0.8Sr_0.2)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.