Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 42: Poster Session II (Nanostructures at surfaces: arrays; Nanostructures at surfaces: Dots, particles, clusters; Nanostructures at surfaces: Other; Nanostructures at surfaces: Wires, tubes; Metal substrates: Adsorption of O and/or H; Metal substrates: Clean surfaces; Metal substrates: Adsorption of organic/bio moledules; Metal substrates: Solid-liquid interfaces; Metal substrates: Adsorption of inorganic molecules; Metal substrates: Epitaxy and growth; Heterogeneous catalysis; Surface chemical reactions; Ab-initio approaches to excitations in condensed matter; Organic, polymeric, biomolecular films– also with adsorbates; Particles and clusters)

O 42.80: Poster

Mittwoch, 25. März 2009, 17:45–20:30, P2

Preparation and electrical characterization of BaO, SrO and Ba_0.7Sr_0.3O thin films on Si(001) — •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

In context with the search for alternative gate oxides in CMOS technology, we have grown high-k BaO, SrO and Ba_0.7Sr_0.3O films of thickness between 5 and 20 nm on clean Si(001) using molecular beam epitaxy of pure metals in ambient oxygen pressure. Especially the BaSr mixture oxide is of high interest, because it grows epitaxially and crystalline on Si(001).
Using Si(001) samples with thick SiO₂ films in combination with lithography, windows of clean Si(001) have been fabricated. Our thin films were only generated on these small squares using a tungsten mask. After preparation, the oxides were capped with 350nm Au and electrically characterized ex-situ.
From capacity-voltage (CV) measurements dielectric constants near the values for volume material were obtained. Furthermore we found very low hysteresis (<5mV) and flatband voltages close to that of the work function difference between Si and Au (+0.65eV). Due to the stoichiometry of these films and well defined interfaces, low leakage current densities (10⁻⁵A/cm²) have been found by current-voltage (IV) measurements. The density of residual defect states at the interface have been derived from CV measurements and will be discussed.