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Analysis of Near-Surface Impurities Using X-Ray Spectroscopy

IP.com Disclosure Number: IPCOM000044636D
Original Publication Date: 1984-Dec-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Boehme, RF: AUTHOR [+3]

Abstract

X-ray absorption spectroscopy is used for qualitative and quantitative chemical analysis of materials, by measurements of the absorption of X-rays by a sample. Each impurity atom in the sample has a distinct absorption edge energy, which provides an identity of the impurities. The magnitude of the change of absorption at the edge is proportional to the concentration of that impurity, where the concentration is made quantitative by using a standard for calibration. This technique can also be used to identify the type of chemical bonding of the impurity atom. Extended X-ray absorption fine structure (EXAFS) above the absorption edge is used to investigate the local atomic structure around impurity atoms, where the measurements give the distances to the atoms surrounding the impurity and the impurity coordination number.

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Analysis of Near-Surface Impurities Using X-Ray Spectroscopy

X-ray absorption spectroscopy is used for qualitative and quantitative chemical analysis of materials, by measurements of the absorption of X-rays by a sample. Each impurity atom in the sample has a distinct absorption edge energy, which provides an identity of the impurities. The magnitude of the change of absorption at the edge is proportional to the concentration of that impurity, where the concentration is made quantitative by using a standard for calibration. This technique can also be used to identify the type of chemical bonding of the impurity atom. Extended X-ray absorption fine structure (EXAFS) above the absorption edge is used to investigate the local atomic structure around impurity atoms, where the measurements give the distances to the atoms surrounding the impurity and the impurity coordination number. However, EXAFS studies of impurities have been mostly limited to bulk amorphous and polycrystalline materials. EXAFS measurements using fluorescence detection for impurity atoms implanted in single crystal hosts, such as As in Si, have been complicated by the elastic scattering which causes the saturation in the fluorescence detector, and by dynamic diffraction which causes distortions in the EXAFS spectra. The technique described here is a simple method for doing X-ray absorption spectroscopy, which is sensitive to the top 2000 ~ thickness of the material under investigation, and which avoids these difficulties. This method is well suited to measurements of absorption spectra, including EXAFS, of As atoms implante...