Core-Level Shift of Si Nanocrystals Embedded in a SiO2 Matrix

Chen, Tu Pei, Liu, Yang, Sun, Chang Qing, Tse, Man Siu, Hsieh, Jang-Hsing, Fu, Yong Qing, Liu, Y. C. and Fung, Steve (2004) Core-Level Shift of Si Nanocrystals Embedded in a SiO2 Matrix. The Journal of Physical Chemistry B, 108 (43). pp. 16609-16612. ISSN 1520-6106

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Abstract

It is expected from existing theories that the core level of Si nanocrystals (nc-Si) embedded in a SiO2 matrix should shift toward a higher binding energy as compared to that of bulk crystalline Si due to quantum size effect. Indeed, it is observed in X-ray photoemission experiments that the Si 2p core level shifts to a higher apparent binding energy by 1−2 eV for all five oxidation states of Sin+ (n = 0, 1, 2, 3, and 4) in the material system of SiO2 containing nc-Si. However, it is found that the core-level shift is due to a charging effect in the material system. After correction for the charging effect by using C 1s binding energy due to contamination on the SiO2 surface, the core level of the oxidation state Si4+ is the same as that of pure SiO2, whereas the core level of the isolated nc-Si with an average size of about 3 nm shifts by ∼ 0.6 eV to a lower binding energy as compared to that of bulk crystalline Si. It is suspected that the core-level shift of the nc-Si toward a lower binding energy is due to the influence of the differential charging between the SiO2 surface layer and the nc-Si underneath.

Item Type:	Article
Subjects:	F200 Materials Science
Department:	Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User:	Becky Skoyles
Date Deposited:	26 Mar 2015 15:01
Last Modified:	12 Oct 2019 19:05
URI:	http://nrl.northumbria.ac.uk/id/eprint/21826

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