1、PD ISO/TR 18394:2016 Surface chemical analysis Auger electron spectroscopy Derivation of chemical information BSI Standards Publication WB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06PD ISO/TR 18394:2016 PUBLISHED DOCUMENT National foreword This Published Document is the UK implementation o
2、f ISO/TR 18394:2016. It supersedes PD ISO/TR 18394:2006 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee CII/60, Surface chemical analysis. A list of organizations represented on this committee can be obtained on request to its secretary. This publicat
3、ion does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2016. Published by BSI Standards Limited 2016 ISBN 978 0 580 85351 7 ICS 71.040.40 Compliance with a British Standard cannot confer immunit
4、y from legal obligations. This Published Document was published under the authority of the Standards Policy and Strategy Committee on 31 May 2016. Amendments issued since publication Date Text affectedPD ISO/TR 18394:2016 ISO 2016 Surface chemical analysis Auger electron spectroscopy Derivation of c
5、hemical information Analyse chimique des surfaces Spectroscopie des lectrons Auger Dduction de linformation chimique TECHNICAL REPORT ISO/TR 18394 Reference number ISO/TR 18394:2016(E) Second edition 2016-05-01PD ISO/TR 18394:2016ISO/TR 18394:2016(E)ii ISO 2016 All rights reserved COPYRIGHT PROTECTE
6、D DOCUMENT ISO 2016, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior w
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8、TR 18394:2016ISO/TR 18394:2016(E)Foreword iv Introduction v 1 Scope . 1 2 Normative references 1 3 T erms and definitions . 1 4 Abbreviated terms 1 5 Types of chemical and solid-state effects in Auger-electron spectra .1 6 Chemical effects arising from core-level Auger-electron transitions 3 6.1 Gen
9、eral . 3 6.2 Chemical shifts of Auger-electron energies . 3 6.3 Chemical shifts of Auger parameters . 4 6.4 Chemical-state plots . 6 6.5 Databases of chemical shifts of Auger-electron energies and Auger parameters . 7 6.6 Chemical effects on Auger-electron satellite structures . 7 6.7 Chemical effec
10、ts on the relative intensities and line shapes of CCC Auger-electron lines . 8 6.8 Chemical effects on the inelastic region of CCC Auger-electron spectra . 9 7 Chemical effects on Auger-electron transitions involving valence electrons 10 7.1 General 10 7.2 Chemical-state-dependent line shapes of CCV
11、 and CVV Auger-electron spectra .10 7.3 Information on local electronic structure from analysis of CCV and CVV Auger- electron line shapes .15 7.4 Novel techniques for obtaining information on chemical bonding from Auger processes 16 Bibliography .21 ISO 2016 All rights reserved iii Contents PagePD
12、ISO/TR 18394:2016ISO/TR 18394:2016(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body
13、 interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotec
14、hnical Commission (IEC) on all matters of electrotechnical standardization. The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO
15、 documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives). Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held res
16、ponsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents). Any trade name used in this document is information giv
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18、ing URL: Foreword Supplementary information. The committee responsible for this document is ISO/TC 201, Surface chemical analysis, Subcommittee SC 7, Electron spectroscopies. This second edition cancels and replaces the first edition (ISO/TR 18394:2006), which has been technically revised.iv ISO 201
19、6 All rights reservedPD ISO/TR 18394:2016ISO/TR 18394:2016(E) Introduction This Technical Report provides guidelines for the identification of chemical effects on X-ray or electron- excited Auger-electron spectra and for using these effects in chemical characterization. Auger-electron spectra contai
20、n information on surface/interface elemental composition as well as on the environment local to the atom with the initial core hole 12345 . Changes in Auger-electron spectra due to alterations of the atomic environment are called chemical (or solid-state) effects. Recognition of chemical effects is
21、very important in proper quantitative applications of Auger-electron spectroscopy and can be very helpful in identification of surface chemical species and of the chemical state of constituent atoms in surface or interface layers. ISO 2016 All rights reserved vPD ISO/TR 18394:2016PD ISO/TR 18394:201
22、6Surface chemical analysis Auger electron spectroscopy Derivation of chemical information 1 Scope This Technical Report provides guidelines for identifying chemical effects in X-ray or electron-excited Auger-electron spectra and for using these effects in chemical characterization. 2 Normative refer
23、ences The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. I
24、SO 18115 (all parts), Surface chemical analysis Vocabulary 3 T erms a nd definiti ons For the purposes of this document, the terms and definitions given in ISO 18115 (all parts) apply. 4 Abbreviated terms CCC core-core-core (Auger-electron transition) CCV core-core-valence (Auger-electron transition
25、) CK Coster-Kronig c-BN cubic boron nitride CVV core-valence-valence (Auger-electron transition) DEAR-APECS Dichroic Effect in Angle Resolved Auger-Photoelectron Coincidence Spectroscopy h-BN hexagonal boron nitride IAE Interatomic Auger Emission ICD Interatomic Coulomb Decay PAES Positron-Annihilat
26、ion-induced Auger Electron Spectroscopy REELS Reflection Electron Energy-Loss Spectroscopy 5 Types of chemical and solid-state effects in Auger-electron spectra Many types of chemical or solid-state effects can be observed in Auger-electron spectra 12345 . Changes in the atomic environment of an ato
27、m ionized in its inner shell can result in a shift of the kinetic energy of the emitted Auger electron. In the case of X-ray-excited Auger-electron spectra, energy shifts of Auger parameters (i.e. kinetic-energy differences between Auger-electron peaks and the photoelectron peaks corresponding to th
28、e core levels involved in the Auger-electron process) can be detected as well. Furthermore, the line shape, the relative intensity and the satellite structure (induced by the intrinsic TECHNICAL REPORT ISO/TR 18394:2016(E) ISO 2016 All rights reserved 1PD ISO/TR 18394:2016ISO/TR 18394:2016(E) excita
29、tion processes) of the Auger-electron lines can be considerably influenced by chemical effects, as can the structure of the energy-loss region (induced by extrinsic, electron-scattering processes) accompanying the intrinsic peaks. Strong chemical effects on the Auger-electron spectral shapes offer w
30、ays of identification of chemical species using the “fingerprint” approach. In the case of electron-excited Auger-electron spectra, the Auger peaks are generally weak features superimposed on an intense background caused to a large extent by the primary electrons scattered inelastically within the s
31、olid sample. As a consequence, the differential Auger-electron spectrum is often recorded (or calculated from the measured spectrum) rather than the direct energy spectrum, facilitating the observation and identification of the Auger-electron peaks and the measurement of the respective Auger transit
32、ion energies. Differentiation can, however, enhance the visibility of random fluctuations in recorded intensities, as shown in Figure 1. If chemical-state information is needed from a direct energy spectrum, then the relative energy resolution of the electron spectrometer should be better than 0,15
33、% (e.g. 0,05 % or 0,02 %). A poorer energy resolution causes a significant broadening of the Auger-electron peaks and prevents observation of small changes of spectral line shapes or peak energies as chemical-state effects in the spectra. A great advantage of electron-excited Auger-electron spectros
34、copy over X-ray excitation with laboratory X-ray source, however, is the possibility of using high lateral resolution and obtaining chemical-state maps of surface nanostructures. NOTE 1 Auger-electron spectra can be reported with the energy scale referenced either to the Fermi level or to the vacuum
35、 level. Kinetic energies with the latter reference are typically 4,5 eV less than those referenced to the Fermi level, but the difference in energies for these two references can vary from 4,0 eV to 5,0 eV since the position of the vacuum level depends on the condition of the spectrometer and may, i
36、n practice, vary with respect to the Fermi level. When energy shifts are determined from spectra recorded on different instruments, use of different energy references should be taken into account. NOTE 2 While the visibility of noise features in a differential spectrum can be reduced by use of a lar
37、ger number of channels in the calculation of the derivative, there may also be distortion of the resulting differential spectrum and loss of fine details associated with chemical-state effects. Key X kinetic energy, eV Y intensity 1 differential spectrum 2 direct spectrum NOTE This figure is reprodu
38、ced from Figure 2.8 of Reference 1. Figure 1 Comparison of direct and differentiated Auger-electron spectra for copper (Cu LMM peaks)2 ISO 2016 All rights reservedPD ISO/TR 18394:2016ISO/TR 18394:2016(E) 6 Chemical effects arising from core-level Auger-electron transitions 6.1 General Core-level (or
39、 core-core-core, CCC) Auger-electron transitions occur when all of the levels involved in the Auger transition belong to the atomic core for the atom of interest. 6.2 Chemical shifts of Auger-electron energies The main effect of any change in the solid-state environment on Auger-electron spectra for
40、 Auger transitions involving core levels is a shift of the Auger energies. This shift results from a change in the core atomic potential due to the changed environment and from a contribution due to the response of the local electronic structure to the appearance of core holes. Auger chemical shifts
41、 are generally larger than the binding-energy shifts of the atomic levels involved in the Auger-electron process because the two-hole final state of the process is more strongly influenced by relaxation effects. This phenomenon is illustrated by the example of aluminium and its oxide in Figure 2 6 .
42、 Large chemical shifts in the energy positions of the Auger-electron lines provide possibilities for chemical-state identification even in the case of electron-excited Auger-electron spectroscopy with, in this case, moderate energy resolution. In X-ray-excited Auger-electron spectra, the peak-to-bac
43、kground intensity ratios are usually larger than those in electron-excited spectra, facilitating accurate determination of peak energies. Recommended Auger electron energies are available for 42 elemental solids 7 . Information on Auger chemical shifts of particular elements can be obtained from han
44、dbooks 891011and online-accessible databases 1213 . Key X kinetic energy, eV Y intensity, counts/s Figure 2 Photoelectron and Auger-electron spectra of an aluminium foil covered by a thin overlayer of aluminium oxide: Excitation with Al and Mo X-rays ISO 2016 All rights reserved 3PD ISO/TR 18394:201
45、6ISO/TR 18394:2016(E) With the advantage of high-energy-resolution analysers, small chemical shifts of Auger-electron lines due to different type of dopants in semiconductors become discernible (for example, the kinetic-energy difference between Si KLL peaks from n-type and p-type silicon is 0,6 eV
46、1 ), allowing chemical-state mapping in spite of the extremely low concentration (far below the detection limits of Auger electron spectroscopy) of the dopants. Figure 3 shows a Si KLL Auger-electron map derived from a cross section of a p-type silicon sample doped with phosphorus by implantation to
47、 obtain n-type Si at the sample surface 1 . Key 1 vacuum 2 n-type Si (implanted with P) 3 p-type Si wafer NOTE 1 A cross section of the sample is shown, and the Auger-electron spectra were excited with an electron beam. NOTE 2 This figure has been reproduced from Figure 5.30 of Reference 1. Figure 3
48、 Silicon KLL Auger-electron map of a p-type silicon sample implanted with phosphorus to produce n-type Si at its surface 6.3 Chemical shifts of Auger parameters Auger parameters, obtained from X-ray-excited Auger-electron spectra, can also be strongly influenced by the environment of the atom emitti
49、ng photoelectrons and Auger electrons 21415161718 . The Auger parameter, , is given by Formula (1):4 ISO 2016 All rights reservedPD ISO/TR 18394:2016ISO/TR 18394:2016(E) (1) where KE( jkl) is the kinetic energy of an Auger transition involving core levels j, k and l of an atom; KE(i) is the kinetic energy of a photoelectron from core level i (which may be the same as the core level j). In order to avoid negative values of the Auger parameter 14
