Berlin 2012 – scientific programme

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DF: Fachverband Dielektrische Festkörper

DF 13: Poster II

DF 13.4: Poster

Wednesday, March 28, 2012, 15:00–17:30, Poster E

Electrical and Structural properties of thermally transformed high-k dielectric Ba_0.7Sr_0.3O thin films on p-Si(100) — •Shariful Islam¹, Dirk Müller-Sajak¹, Alexandr Cosceev², Herbert Pfnür¹, and Karl R. Hofmann² — ¹Leibniz-Universität Hannover, Inst. f. Festkörperphysik — ²Leibniz-Universität Hannover, Bauelemente der Mikro- und Nanoelektronik

Crystalline thin films of Ba_0.7Sr_0.3O were tested as a high-k dielectric material deposited on p-Si(100) substrate. The valence band offset and conduction band offset between p-Si(100) and Ba_0.7Sr_0.3O was ∼2.3eV and ∼1.0eV respectively.
It was observed that Ba_0.7Sr_0.3O was stable up to 400⁰C. At higher temperature silicon from the substrate diffuses into the oxide and forms a silicate, as found by XPS. SPA-LEED measurements showed that the silicate phase is amorphous once the reaction is completed (550⁰C). Electron Energy Loss Spectroscopy (EELS) of this silicate phase revealed a higher band gap ( ∼6eV) compared to crystalline Ba_0.7Sr_0.3O ( ∼4.3eV). XPS measurements prove that the silicate phase is more stable in ambient conditions than Ba_0.7Sr_0.3O. Extrapolations of dielectric constants at various conditions predict that also this silicate may be usable as a high-k dielectric.