1、Designation: E984 06E984 12Standard Guide forIdentifying Chemical Effects and Matrix Effects in AugerElectron Spectroscopy1This standard is issued under the fixed designation E984; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, th
2、e year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide outlines the types of chemical effects and matrix effects which are observed in Auger electron sp
3、ectroscopy.1.2 Guidelines are given for the reporting of chemical and matrix effects in Auger spectra.1.3 Guidelines are given for utilizing Auger chemical effects for identification or characterization.1.4 This guide is applicable to both electron excited and X-ray excited Auger electron spectrosco
4、py.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced
5、Documents2.1 ASTM Standards:2E673 Terminology Relating to Surface Analysis (Withdrawn 2012)3E827 Practice for Identifying Elements by the Peaks in Auger Electron SpectroscopyE983 Guide for Minimizing Unwanted Electron Beam Effects in Auger Electron SpectroscopyE996 Practice for Reporting Data in Aug
6、er Electron Spectroscopy and X-ray Photoelectron Spectroscopy2.2 Other Documents:ISO 18118:2004 Surface Chemical AnalysisAuger Electron Spectroscopy and X-ray Photoelectron SpectroscopyGuide tothe Use of Experimentally Determined Relative Sensitivity Factors for the Quantitative Analysis of Homogeno
7、us Materials3. Terminology3.1 Terms used in Auger electron spectroscopy are defined in Terminology E673.4. Significance and Use4.1 Auger electron spectroscopy is often capable of yielding information concerning the chemical and physical environment ofatoms in the near-surface region of a solid as we
8、ll as giving elemental and quantitative information. This information is manifestedas changes in the observed Auger electron spectrum for a particular element in the specimen under study compared to the Augerspectrum produced by the same element when it is in some reference form. The differences in
9、the two spectra are said to be dueto a chemical effect or a matrix effect. Despite sometimes making elemental identification and quantitative measurements moredifficult, these effects in the Auger spectrum are considered valuable tools for characterizing the environment of the near-surfaceatoms in a
10、 solid.5. Defining Auger Chemical Effects and Matrix Effects5.1 In general, Auger chemical and matrix effects may result in (a) a shift in the energy of an Auger peak, (b) a change in theshape of an Auger electron energy distribution, (c) a change in the shape of the electron energy loss distributio
11、n associated with1 This guide is under the jurisdiction of ASTM Committee E42 on Surface Analysis and is the direct responsibility of Subcommittee E42.03 on Auger ElectronSpectroscopy and X-Ray Photoelectron Spectroscopy.Current edition approved Nov. 1, 2006Nov. 1, 2012. Published November 2006Decem
12、ber 2012. Originally approved in 1984. Last previous edition approved in 20012006as E984 95 (2001).E984 06. DOI: 10.1520/E0984-06.10.1520/E0984-12.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standard
13、svolume information, refer to the standards Document Summary page on the ASTM website.3 The last approved version of this historical standard is referenced on www.astm.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes
14、 have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official
15、 document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1anAuger peak, or (d) a change in theAuger signal strengths of anAuger transition. The above changes may be due to the bondingor chemical environment of the element (chemical ef
16、fect) or to the distribution of the element or compound within the specimen(matrix effect).5.2 The Auger chemical shift is one of the most commonly observed chemical effects. A comparison can be made to the morefamiliar chemical shifts in XPS (X-ray photoelectron spectroscopy) photoelectron lines, w
17、here energy shifts are caused by changesin the ionic charge on an atom, the lattice potential at that atomic site, and the final-state relaxation energy contributed by adjacentatoms (1 and 21 and 2).4 Frequently an Auger chemical shift is larger than an XPS chemical shift (see Fig. 1) because the Au
18、gerprocess involves a two-hole final state for the atom which is more strongly influenced by extra-atomic relaxation. Coverage by gasadsorbates on metal surfaces may also cause shifts in the metal Auger peak energies (3). The magnitude of the Auger chemicalshift will usually be different from the XP
19、S photoelectron shift because the Auger process involves a two-hole final state for theatom which is moreBand bending across junctions between p- and n-type materials shift the energy levels of each material relativeto the Fermi level resulting in an apparent shift in theAuger line energies. This ef
20、fect has been observed for p-n junctions of silicon(see Fig. 2strongly) influenced(4) by extra-atomic relaxation. Frequently an Auger chemical shift isand those of heteroepitaxiallayers such as GaN/AlGaN (see Fig. 3larger) than (5an XPS chemical shift (see Fig. 1).5.2.1 Related to chemical shifts is
21、 the (modified) Auger parameter, defined as the sum of the photoelectron binding energy andthe Auger electron kinetic energy (46). Because the Auger parameter is the difference between two line energies of the sameelement of the same specimen, it is independent of any electrical charging of the spec
22、imen and spectrometer energy reference level,making it easier to identify chemical states of elements in insulating specimens. Naturally, since both photoelectron lines andAugerlines must be measured, the Auger parameter can only be used with X-ray excited spectra.5.3 The second category of chemical
23、 information from Auger spectroscopy is the Auger lineshapes observed for transitionsinvolving valence electron orbitals. Shown in Fig. 24 and Fig. 3are selectedvariations in the lineshapes for electron-excited carbonKLLfor different phases of carbon, in Fig. 5and are lineshapes for carbon KLLfor di
24、fferent chemical environments of carbon, andin Fig. 6 are lineshapes for aluminum LVV Auger transitions for different chemical states of those elements. levels of oxidation.While it is possible to relate the prominent peaks in theAuger spectrum to transitions from particular bands in the density of
25、states(for solids) or to particular molecular orbitals (for molecules) (57), this is not an easy task. The large number of possible two-holefinal states, taken together with shake-up and shake-off transitions and uncertainty on all their final energies and intensities makethe job of constructing a v
26、alence orbital density map from the Auger spectrum next to impossible for all but the simplest systems.Further, some spectra exhibit a quasiatomic character (68). Accordingly, most studies use the “fingerprint” approach whenattempting to identify unknown species based on theirAuger lineshape. Of cou
27、rse reference spectra are necessary in this approach4 The boldface numbers in parentheses refer to the references at the end of this standard.FIG. 1 Comparison of X-rayX-Ray Excited Cd MNN Auger and 3d Photoelectron Energy Shifts for Cd Metal, CdO, and CdF2 (Ref(Ref.1316)E984 122for a positive ident
28、ification. “Surface Science Spectra” is an international journal and database devoted to archiving surface sciencespectra of technological and scientific interest spectra from surfaces and interfaces (179).5.4 Other effects besides energy shifts and valence lineshapes may be classified as chemical e
29、ffects in Auger spectroscopy. Forinstance, many body effects in metals, such as plasmons, may make the lineshapes of Auger transitions of atoms in the metallicstate very different from theAuger lineshapes for other chemical states, even for transitions involving only core-type electrons,Aland Mg (71
30、0). In single crystals, diffraction effects will produce different lineshapes (811). Relative intensities of several Augertransitions may change, either from attenuation of overlayers (912), or from different chemical states resulting in different Augertransition probabilities (1013 and 1114). Phono
31、n broadening and inelastic electron energy loss effects will result in differentlinewidths and backgrounds for gases, adsorbates, and condensed phases (1215).5.5 For both X-ray and electron excited Auger spectra, quantitative corrections for matrix effects are discussed in detail inISO 18118:2004.FI
32、G. 42 SulfurSilicon LVV Auger Spectra for AgSeven2SO4, Na Samples2SO4, K of2SO4, Na Differing2SO3, K Dopant2SO3, AgConcentrations2S, CdS (Ref and Types (Ref. 164)FIG. 3 Auger Spectra for p- and n- Type GaN Heteroepitaxial, the Inset Shows the Ga LMM Lines (Ref. 5)FIG. 24 Carbon KLL Auger Spectra for
33、 MoDiamond,2C, SiC, Graphite, and Diamond (Ref Amorphous Carbon (Refs. 1417 and 18)E984 1236. Guidelines for Reporting Auger Chemical and Matrix Effects6.1 In general, the guidelines outlined in Practice E996 should be used. This practice covers reporting of the spectrometer,specimen preparation, ex
34、citation source, analyzer and detector modes, and data processing.Also, if measures were taken to controldamage or charging of the specimen, report those conditions in a manner consistent with Guide E983.6.1.1 Practice E827 should be used to confirm the elemental identification. The elemental inform
35、ation should be consistent withthe presumed chemical state identification.6.1.2 When reporting chemical and matrix effects in an Auger spectrum, the main feature of interest is the Auger peak energy(reported in eV). This is the energy of the largest negative excursion in the dN/dE spectrum or the mo
36、st intense peak in the N(E)spectrum. (Of course, these two peak positions measurements will have different energy values.) The energy location of the majorAuger peak should be in agreement with the reference value, consistent with the experimental parameters and calibrations asdiscussed in Practice
37、E996.FIG. 5 A comparison of the Carbon KLL Auger Lineshape with increasing chromium content in a gradient layer of -C/Si(100) showingthe evolution of the C KLL lineshape from one typical of graphite (0 % Cr) to one typical of a metal carbide (44 % Cr) (Ref. 19)(a) Almost no Oxidation (b) Partial Oxi
38、dation (c) After Oxidation hasReached a Satura-tion StageFIG. 36 Changes in the Aluminum LVV Auger spectrum asOxygen is Absorbed on the Surface (Ref(Ref. 1520)E984 1246.1.3 The reference level for the energy scale of the electron energy analyzer and the method for calibrating the energy scaleshould
39、be specified. The relative peak energy shifts between the chemical states of interest and that element in its elemental state(or some other standard state) should also be reported.6.1.4 Other spectral features which may be useful include the number, relative energy positions, and relative signal str
40、engthsof the secondary peaks. The reporting of these values should also be in agreement with the reference value and consistent withthe experimental parameters and calibrations discussed in Practice E996.6.2 When spectra are presented for publication, the energy range should be wide enough that the
41、shape of the background oneither side of the Auger line is apparent. Shown in Fig. 47 are Auger spectra for several sulfur-containgsulfur-containingcompounds, and in Table 1 information from these spectra.7. Keywords7.1 Auger electron spectroscopy; chemical effect; matrix effect; spectroscopyREFEREN
42、CES(1) Wagner, C. D., and Biloen, P. “X-ray Excited Auger and Photoelectron Spectra of Partially Oxidized Magnesium Surfaces: The Observation ofAbnormal Chemical Shifts,” Surface Science, Vol 35, 1973, pp. 8295.(2) Wagner, C. D., “Chemical Shifts of Auger Lines, and the Auger Parameter,” Discussions
43、 of the Faraday Society, Vol 60, 1975, pp. 291300.(3) Haas, T. W., and Grant, J. T., “Chemical Shifts inAuger Electron Spectroscopy from the Initial Oxidation of Ta(110),” Physics Letters, Vol 30A, 1969,p. 272.(4) Werner, W. S. M., and Lakatha, H., “Auger voltage contrast imaging for the delineation
44、 of two-dimensional junctions in cross-sectionedmetal-oxide-semiconductor devices,” Journal of Vacuum Science and Technology, B, Vol 16, 1998, pp. 420425.(5) Ecke, G., Niebelshtz, M., Kosiba, R., Rossow, U., Cimalla, V., Liday, J., Vogrini, P., Pezoldt, J., Lebedev, V., and Ambacher, O., Journal ofE
45、lectrical Engineering, Vol 57, 2006, pp. 354359.TABLE 1 Sulfur in Sulfur CompoundsNOTE 1Data Compiled From Auger Spectra (Ref(Ref. 1619).Compound Electron Excited LVVA,B New PeakA EA,C X-ray Excited LVVA,D Auger Parameter PlusPhoton EnergyA,DK2SO4 138.7 123.9 11.7 . .Ag2SO4 141.7 127.4 8.7 . .Na2SO4
46、 138.3 123.0 12.1 . .Na2SO3 139.1 124.8 11.3 . .K2SO3 139.4 124.5 11.0 . .Ag2S 150.4 . . 149.3 516.9A Energy in eV.B Zero point of derivative spectra.C Ag2S used for reference.D Al K X rays.FIG. 7 Sulfur LVV Auger Spectra for Ag2SO4, Na2SO4, K2SO4, Na2SO3, K2SO3, Ag2S, CdS (Ref. 21)E984 125(6) Wagne
47、r, C.A., Gale, L. H., and Raymond, R. H., “Two-Dimensional Chemical State Plots:AStandardized Data Set for Use in Identifying ChemicalStates by X-ray Photoelectron Spectroscopy,” Analytical Chemistry, Vol 51, 1979, pp. 466482.(7) Jennison, D. R., “Understanding Core-Valence-Valence Auger Lineshapes,
48、” Journal of Vacuum Science and Technology, Vol 20, 1982, pp. 548554.(8) SawatskySawatsky, G. A., “Quasiatomic Auger Spectra in Narrow-Band Metals,” Physical Review Letters, Vol 39, 1977, pp. 504-507.(9) Surface Science Spectra, published by American Vacuum Society.(10) Palmberg, P. W., “Quantitativ
49、e Analysis of Solid Surfaces by Auger Electron Spectroscopy,” Analytical Chemistry, Vol 45, 1973, pp. 549A556A.(11) Chang, C. C., “Intensity Variations in Auger Spectra Caused by Diffraction,” Applied Physics Letters, Vol 31, 1977, pp. 304306.(12) Holloway, P. H., “Thickness Determination of Ultrathin Films by Auger Electron Spectroscopy,” Journal of Vacuum Science and Technology, Vol12, 1975, pp. 14181422.(13) Weissmann, R., “Intensity Ratios of the KL1L1, KL23L23 OxygenAuger Lines in Different Compounds,” Solid State Communications, Vol 31, 1979,pp. 3
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