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Titolo:
Atomic structure of carbon-induced Si(001)c(4X4) reconstruction as a Si-Sihomodimer and C-Si heterodimer network - art. no. 035306
Autore:
Simon, L; Stoffel, M; Sonnet, P; Kubler, L; Stauffer, L; Selloni, A; De Vita, A; Car, R; Pirri, C; Garreau, G; Aubel, D; Bischoff, JL;
Indirizzi:
Fac Sci, LPSE, CNRS, UPRESA 7014, F-68093 Mulhouse, France Fac Sci Mulhouse France F-68093 S, UPRESA 7014, F-68093 Mulhouse, France Princeton Univ, Dept Chem, Princeton, NJ 08544 USA Princeton Univ Princeton NJ USA 08544 Dept Chem, Princeton, NJ 08544 USA Univ Trieste, Dipartimento Engn Mat, I-34127 Trieste, Italy Univ Trieste Trieste Italy I-34127 ento Engn Mat, I-34127 Trieste, Italy Princeton Mat Mat, Princeton, NJ 08544 USA Princeton Mat Mat Princeton NJUSA 08544 Mat Mat, Princeton, NJ 08544 USA
Titolo Testata:
PHYSICAL REVIEW B
fascicolo: 3, volume: 6403, anno: 2001,
pagine: 5306 -
SICI:
0163-1829(20010715)6403:3<5306:ASOCSR>2.0.ZU;2-C
Fonte:
ISI
Lingua:
ENG
Soggetto:
RAY PHOTOELECTRON DIFFRACTION; EPITAXIAL SI1-YCY ALLOYS; SI(100) SURFACE; C(4X4) RECONSTRUCTION; MONOHYDRIDE; ENERGETICS; DIHYDRIDE; HYDROGEN; PHASES; LAYERS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
--discip_EC--
Citazioni:
34
Recensione:
Indirizzi per estratti:
Indirizzo: Kubler, L Fac Sci, LPSE, CNRS, UPRESA 7014, F-68093 Mulhouse, France Fac Sci Mulhouse France F-68093 7014, F-68093 Mulhouse, France
Citazione:
L. Simon et al., "Atomic structure of carbon-induced Si(001)c(4X4) reconstruction as a Si-Sihomodimer and C-Si heterodimer network - art. no. 035306", PHYS REV B, 6403(3), 2001, pp. 5306

Abstract

A combination of low-energy electron diffraction, x-ray and ultraviolet photoelectron spectroscopy, and scanning-tunneling microscopy studies, in conjunction with ab initio calculations leads us to suggest a model for the carbon (C)-induced Si(001)c(4x4) atomic structure. This surface superstructure is obtained in a defined range of C2H4 exposures at 600 degreesC. Experimental probes show that the c(4x4) superstructure involves C atoms in both surface and subsurface sites. This is reflected in well-marked features in photoemission valence- and core-level spectra. Surface carbon atoms are stabilized in Si-C heterodimers, with a surface density of about 0.25 monolayer(ML) [i.e., two C atoms per c(4x4) unit cell of eight atoms]. In the subsurface region, carbon atoms substitute for Si atoms in well-defined sites ofthe third or fourth layers of the Si substrate. The subsurface C density increases with C2H4 exposure time up to a limit value of about 0.5 ML, within the c(4x4) surface structure. Further exposure disrupts the c(4x4) reconstruction and leads to a (2x1) low-energy electron diffraction pattern. Interaction with atomic hydrogen shows that the surface contains a mixture of heterodimers (Si-C) and homodimers (Si-Si), with an 1:1 proportion. These assignments are supported by first-principle calculations, which yield valence band and core level states in fairly good agreement with the experiment. Furthermore, total energy calculations strongly favor C incorporation in surface Si-C dimers and in third and fourth layer sites, and rule out C incorporation in sites of the second Si layer. The most stable c(4x4) surface configuration, suggested by our calculations, consists of alternate Si-C and Si-Si dimer lines. In such a configuration, surface carbon atoms in Si-C dimers induce a surface stress that leads to charge redistribution and atomicrelaxation of the adjacent Si-Si dimers, consistent with scanning-tunneling microscopy images. Additional C atoms (in excess of those accommodated insurface sites) are forced in selected compressive (alpha) sites of the third and fourth layers. This model is discussed with respect to the previous models published in the literature.

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Documento generato il 20/09/20 alle ore 03:37:52