Comparison of hard and soft x-ray photoelectron spectra of silicon

F. Offi, W. S. M. Werner, M. Sacchi, P. Torelli, M. Cautero, G. Cautero, A. Fondacaro, S. Huotari, G. Monaco, G. Paolicelli, W. Smekal, G. Stefani, and G. Panaccione
Phys. Rev. B 76, 085422 – Published 17 August 2007

Abstract

A detailed comparison of the surface sensitivity of x-ray photoemission spectroscopy for hard and soft x rays is presented and discussed. Electron scattering parameters and their energy dependence are given for Si and two Si spectra are analyzed: a MgKα (hν=1253.6eV) excited spectrum of the Si2p and 2s lines and a hard x-ray excited spectrum (hν=5925eV) of the Si1s line. The differential inelastic scattering characteristics for Si are extracted from reflection electron energy loss spectra taken at energies of 1500 and 4000eV. Using these scattering characteristics and electron mean free paths from the literature, simulated spectra are compared with experiment. The experimental spectra are deconvoluted to give the true intrinsic line shape corresponding to the theoretical collision statistics when interference effects between intrinsic and extrinsic scattering are neglected. The magnitude of interference effects cannot be assessed by our analysis. Within the (unknown) uncertainty introduced by neglecting interference effects, it is possible to determine the relative intensity of intrinsic and extrinsic excitations. In this way, it is found that in the case of the soft x-ray excited photoelectron spectrum of the shallower electronic shells (2p and 2s), intrinsic plasmon creation is rather weak, and the apparent asymmetric line shape of the spectrum might be interpreted as the fact that electron-hole pair creation dominates the intrinsic loss spectrum, while an alternative explanation in terms of surface core level shifted components is also proposed. For the deeper core electronic shell, probed with hard x rays, the opposite situation is observed: while intrinsic electron-hole pair creation was not observed, a strong contribution of intrinsic plasmon losses of about 30% was seen.

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  • Received 12 October 2006

DOI:https://doi.org/10.1103/PhysRevB.76.085422

©2007 American Physical Society

Authors & Affiliations

F. Offi1, W. S. M. Werner2, M. Sacchi3, P. Torelli4, M. Cautero5, G. Cautero5, A. Fondacaro1,*, S. Huotari6, G. Monaco6, G. Paolicelli4, W. Smekal2, G. Stefani1, and G. Panaccione7

  • 1CNISM and Dipartimento di Fisica, Università Roma Tre, Via della Vasca Navale 84, I-00146 Rome, Italy
  • 2Institut für Allgemeine Physik, Vienna University of Technology, Wiedner Hauptsraße 8-10, A-1040 Vienna, Austria
  • 3Synchrotron Soleil, Boîte Postale 48, F-91142 Gif-sur-Yvette, France and Laboratoire de Chimie Physique-Matière et Rayonnement, Universté P. et M. Curie, UMR 7614, 11 rue P. et M. Curie, F-75005 Paris, France
  • 4CNR-INFM-S3, Via Campi 213/A, I-41100 Modena, Italy
  • 5Sincrotrone Trieste S.C.p.A., Strada Statale 14 km 163.5, Area Science Park, Basovizza, I-34012 Trieste, Italy
  • 6European Synchrotron Radiation Facility, Boîte Postale 220, F-38042 Grenoble, France
  • 7Laboratorio Nazionale TASC-INFM-CNR, Area Science Park, Basovizza Strada Statale 14 km 163.5, I-34012 Trieste, Italy

  • *Present address: European Synchrotron Radiation Facility, B.P. 220, F-38042 Grenoble, France.

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Issue

Vol. 76, Iss. 8 — 15 August 2007

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