Work function in Si1-xGex heterostructures with Ge content in the 6% to 49% range was studied with high energy resolution by combining Kelvin force microscopy and X-ray photoelectron emission microscopy. Although the two methods are based on distinct physical mechanisms, we show that both techniques give the same work function differences between each Si1-xGex layer, as small as 20 meV. To detect such small work function differences, we put in evidence the necessity of preparing the Si1-xGex sample surface with polishing, HF etching and Ar+ sputtering. Such surface preparation allows, in principle, to reduce the deleterious influence of surface states, coming for instance from carbon atoms or native oxide, on quantitative work function extraction. We show in this paper that even after such a sample surface preparation, a strong band bending can be present, which causes a contrast inversion on the surface of the material and yields an artificially lower surface work function with respect to theoretical values. By using density functional theory simulations, we demonstrate that such inversion is likely due to residual carbon present on the surface.

Work Function Measurement of Silicon Germanium Heterostructures Combining Kelvin Force Microscopy and X-ray Photoelectron Emission Microscopy / Pouch, Sylvain; Amato, Michele; Bertocchi, Matteo; Ossicini, Stefano; Chevalier, Nicolas; Melin, Thierry; Hartmann, Jean Michel; Renault, Olivier; Delaye, Vincent; Mariolle, Denis; Borowik, Lukasz. - In: JOURNAL OF PHYSICAL CHEMISTRY. C. - ISSN 1932-7447. - STAMPA. - 119:47(2015), pp. 26776-26782. [10.1021/acs.jpcc.5b09278]

Work Function Measurement of Silicon Germanium Heterostructures Combining Kelvin Force Microscopy and X-ray Photoelectron Emission Microscopy

BERTOCCHI, MATTEO;OSSICINI, Stefano;
2015

Abstract

Work function in Si1-xGex heterostructures with Ge content in the 6% to 49% range was studied with high energy resolution by combining Kelvin force microscopy and X-ray photoelectron emission microscopy. Although the two methods are based on distinct physical mechanisms, we show that both techniques give the same work function differences between each Si1-xGex layer, as small as 20 meV. To detect such small work function differences, we put in evidence the necessity of preparing the Si1-xGex sample surface with polishing, HF etching and Ar+ sputtering. Such surface preparation allows, in principle, to reduce the deleterious influence of surface states, coming for instance from carbon atoms or native oxide, on quantitative work function extraction. We show in this paper that even after such a sample surface preparation, a strong band bending can be present, which causes a contrast inversion on the surface of the material and yields an artificially lower surface work function with respect to theoretical values. By using density functional theory simulations, we demonstrate that such inversion is likely due to residual carbon present on the surface.
4-nov-2015
119
47
26776
26782
Work Function Measurement of Silicon Germanium Heterostructures Combining Kelvin Force Microscopy and X-ray Photoelectron Emission Microscopy / Pouch, Sylvain; Amato, Michele; Bertocchi, Matteo; Ossicini, Stefano; Chevalier, Nicolas; Melin, Thierry; Hartmann, Jean Michel; Renault, Olivier; Delaye, Vincent; Mariolle, Denis; Borowik, Lukasz. - In: JOURNAL OF PHYSICAL CHEMISTRY. C. - ISSN 1932-7447. - STAMPA. - 119:47(2015), pp. 26776-26782. [10.1021/acs.jpcc.5b09278]
Pouch, Sylvain; Amato, Michele; Bertocchi, Matteo; Ossicini, Stefano; Chevalier, Nicolas; Melin, Thierry; Hartmann, Jean Michel; Renault, Olivier; Delaye, Vincent; Mariolle, Denis; Borowik, Lukasz
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11380/1085028
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