Analytical Techniques: Auger Electron Spectroscopy
A. Joshi, Lockheed Palo Alto Research Laboratory
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General Use |
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- Compositional analysis of the 0- to 3-nm region near the surface for all elements except H and He |
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- Depth-compositional profiling and thin film analysis |
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- High lateral resolution surface chemical analysis and
inhomogeneity studies to determine compositional variations
in areas |
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- Grain-boundary and other interface analyses facilitated by fracture |
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- Identification of phases in cross sections |
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Examples of Applications |
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- Analysis of surface contamination of materials to investigate its role in such properties as corrosion, wear, secondary electron emission, and catalysis |
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- Identification of chemical-reaction products, for example, in oxidation and corrosion |
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- In-depth compositional evaluation of surface films, coatings, and thin films used for various metallurgical surface modifications and microelectronic applications |
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- Analysis of grain-boundary chemistry to evaluate the role of boundary precipitation and solute segregation on mechanical properties, corrosion, and stress corrosion cracking phenomena |
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Samples |
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- Form: Solids (metals, ceramics, and organic materials) with relatively low vapor pressures (< 10 -8 torr at room temperature). Higher vapor pressure materials can be handled by sample cooling. Similarly, many liquid samples can be handled by sample cooling or by applying a thin film onto a conductive substrate |
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- Size: Individual powder particles as small as
1 |
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- Surfacetopography: Flat surfaces are preferable, but
rough surfaces can be analyzed in selected small areas (~ 1
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- Preparation: Frequently none. Samples must be free of fingerprints, oils, and other high vapor pressure materials |
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Limitations |
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- Insensitivity to hydrogen and helium |
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- The accuracy of quantitative analysis is limited to
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- Electron beam damage can severely limit useful analysis of organic and biological materials and occasionally ceramic materials |
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- Electron beam charging may limit analysis when examining highly insulating materials |
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- Quantitative detection sensitivity for most elements is from 0.1 to 1.0 at. % |
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Estimated Analysis Time |
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- Usually under 5 min for a complete survey spectrum from 0 to 2000 eV. Selected peak analyses for studying chemical effects, Auger elemental imaging, and depth profiling generally take much longer |
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Capabilities of Related Techniques |
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- X-ray photoelectron spectroscopy: Provides compositional and chemical binding state information, relatively nondestructive |
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- Ion scattering spectroscopy: Provides superb top atomic layer information, specificity of surface atomic bonding in selected cases, and surface composition and depth profiling information |
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- Secondary ion mass spectroscopy: High elemental detection sensitivity from part per million to part per billion levels; surface compositional information; depth profiling capability; sensitivity for all elements, including hydrogen and helium |
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- Electron probe: Analysis to 1- |
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- Analytical electron microscopy: Chemical analysis in conjunction with high-resolution microscopy |
Reprinted with permission of ASM International®.
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