A SrF2 ultrathin barrier layer on Si(001) is used to form a sharp interface and block reactivity and intermixing between the semiconductor and a Yb2O3 overlayer. Yb2O3/Si(001) and Yb2O3/SrF2/Si(001) interfaces grown in ultra high vacuum by molecular beam epitaxy are studied by photoemission and x-ray absorption fine structure. Without the fluoride interlayer, Yb2O3/Si(001) presents an interface reacted region formed by SiOx and/or silicate compounds, which is about 9 A ̊ thick and increases up to 14–15 A ̊ after annealing at 500–700 ◦C. A uniform single layer of SrF2 molecules blocks intermixing and reduces the oxidized Si region to 2.4 A ̊ after deposition and to 3.5 A ̊ after annealing at 500 ◦C. In both cases we estimate a conduction band offset and a valence band offset of ∼1.7 eV and 2.4 eV between the oxide and Si, respectively. X-ray absorption fine structure measurements at the Yb LIII edge suggest that the Yb oxide films exhibit a significant degree of static disorder with and without the fluoride barrier. Sr K edge measurements indicate that the ultrathin fluoride films are reacted, with the formation of bonds between Si and Sr; the Sr–Sr and Sr–F interatomic distances in the ultrathin fluoride barrier film are relaxed to the bulk value.

Atomic and electronic structure of ultrathin fluoride barrier layers at the oxide/Si interface / PASQUALI, Luca; MONTECCHI, Monica; NANNARONE, Stefano; F., Boscherini. - In: JOURNAL OF PHYSICS. CONDENSED MATTER. - ISSN 0953-8984. - STAMPA. - 23:(2011), pp. 355003-1-355003-11. [10.1088/0953-8984/23/35/355003]

Atomic and electronic structure of ultrathin fluoride barrier layers at the oxide/Si interface

PASQUALI, Luca;MONTECCHI, Monica;NANNARONE, Stefano;
2011

Abstract

A SrF2 ultrathin barrier layer on Si(001) is used to form a sharp interface and block reactivity and intermixing between the semiconductor and a Yb2O3 overlayer. Yb2O3/Si(001) and Yb2O3/SrF2/Si(001) interfaces grown in ultra high vacuum by molecular beam epitaxy are studied by photoemission and x-ray absorption fine structure. Without the fluoride interlayer, Yb2O3/Si(001) presents an interface reacted region formed by SiOx and/or silicate compounds, which is about 9 A ̊ thick and increases up to 14–15 A ̊ after annealing at 500–700 ◦C. A uniform single layer of SrF2 molecules blocks intermixing and reduces the oxidized Si region to 2.4 A ̊ after deposition and to 3.5 A ̊ after annealing at 500 ◦C. In both cases we estimate a conduction band offset and a valence band offset of ∼1.7 eV and 2.4 eV between the oxide and Si, respectively. X-ray absorption fine structure measurements at the Yb LIII edge suggest that the Yb oxide films exhibit a significant degree of static disorder with and without the fluoride barrier. Sr K edge measurements indicate that the ultrathin fluoride films are reacted, with the formation of bonds between Si and Sr; the Sr–Sr and Sr–F interatomic distances in the ultrathin fluoride barrier film are relaxed to the bulk value.
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355003-1
355003-11
Atomic and electronic structure of ultrathin fluoride barrier layers at the oxide/Si interface / PASQUALI, Luca; MONTECCHI, Monica; NANNARONE, Stefano; F., Boscherini. - In: JOURNAL OF PHYSICS. CONDENSED MATTER. - ISSN 0953-8984. - STAMPA. - 23:(2011), pp. 355003-1-355003-11. [10.1088/0953-8984/23/35/355003]
Pasquali, Luca; Montecchi, Monica; Nannarone, Stefano; F., Boscherini
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11380/665653
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