Berlin 2015 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 8: High-k and Low-k Dielectrics (DS with DF)

DF 8.2: Vortrag

Dienstag, 17. März 2015, 11:30–11:45, H 0111

Structuring and interface manipulation of ultra-thin silicate films on a Si(001) surface — •Shariful Islam¹, Karl Hofmann², and Herbert Pfnür¹ — ¹Institut für Festkörperphysik (ATMOS), Leibniz Universität Hannover — ²Inst. f. Bauelemente der Mikroelektronik, Leibniz Universität Hannover

The dielectric-substrate interface plays a very important role on the growth condition and on the chemical, structural and kinetic properties of dielectric layers. Some very important properties like the sharpness of the interface, trap densities and band alignment also influenced by the cleanliness of substrate surface. We found the crystalline high-k silicate (Ba_0.8Sr_0.2)₂SiO₄ and Ba₂SiO₄ to have dielectric constants ∼ 18 and ∼ 20 respectively. We studied the silicates elaborately both on structured and unstructured Si(001) surface after depositing both at room and at high temperature (650^∘C). In addition to the spectroscopic measurements (XPS, SPA-LEED, EELS, AFM and TEM) we performed electrical measurements (C-V & I-V) of the silicate as an alternate gate dielectric in a MOS diode to study the dielectric-substrate interface in detail. The crystalline orthorhombic Ba₂SiO₄ grown here has a band gap of E_G = 5.7eV, an interface trap density D_it∼ 10¹² eV⁻¹cm⁻², very low hysteresis <0.5mV, band offset >2eV, leakage current <6 mA/cm² at +1V; additional structural and electrical properties will be discussed.