Berlin 2015 – scientific programme
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DS: Fachverband Dünne Schichten
DS 15: High-k and Low-k Dielectrics (joint session with DF)
DS 15.2: Talk
Tuesday, March 17, 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 (Ba0.8Sr0.2)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 EG = 5.7eV, an interface trap density Dit∼ 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.