Dresden 2011 – scientific programme
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DS: Fachverband Dünne Schichten
DS 42: Poster I: Progress in Micro- and Nanopatterning: Techniques and Applications (jointly with O); Spins in Organic Materials; Ion Interactions with Nano Scale Materials; Organic Electronics and Photovoltaics; Plasmonics and Nanophotonics (jointly with HL and O); High-k and Low-k Dielectrics (jointly with DF); Organic Thin Films; Nanoengineered Thin Films; Layer Deposition Processes; Layer Properties: Electrical, Optical, and Mechanical Properties; Thin Film Characterisation: Structure Analysis and Composition; Application of Thin Films
DS 42.125: Poster
Wednesday, March 16, 2011, 15:00–17:30, P1
Thermal stability of BaSrO thin films and the influence of Al intermediate layers to the electrical properties of high-k Si(001)/BaSrO/Au MOS diodes — •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
MOS diodes with crystalline Ba0.7Sr0.3O gate oxide and Au gate metal on n- and p-Si(001) were produced,
which have a dielectric constant of єr≈28. The oxides were
grown on structured Si(001) in a UHV chamber by MBE in oxygen ambient conditions and
capped with 100nm Au for ex-situ electrical measurements. I-V measurements show low
leakage currents compared to SiO2 with the same EOT. From C-V measurements we
extracted with the Terman method a density of interface states, Dit, of only
≈1010eV−1cm−2.
We tested the thermal stability of these oxides and investigated them with X-Ray Photoelectron Spectroscopy (XPS).
They are fully stable up to 450∘C but convert to other chemical species, most likely silicates, at higher temperatures. But even at 700∘C no formation of SiO2 at the interface to Si was detectable.
To improve the adhesion between the Au gate metal and the oxide we evaporated a thin layer of Al at the Au/oxide interface. This causes a thickness dependent shift of the flatband voltage. We will present our XPS measurements of the chemical origin of this shift.