For local structure analyses of low dimensional structures in semiconductors, such as defects, interfaces and surfaces, a new site-selective x-ray absorption fine structure (XAFS) measurement, 'capacitance XAFS' method, is proposed. In this method, the x-ray photon energy dependence of a capacitance involved in various diode structures is measured. The capacitance is changed by an x-ray induced photoemission of a localized electron trapped in the low dimensional structures. Since the photoemission originates from the x-ray absorption of only the low dimensional structures, the site-selective analysis may be realized. Experiments using Schottky barrier diodes of AlGaAs: Se with a defect, 'DX center', successfully indicate the site-selective XAFS spectra of the defect atom.
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