USE OF PARALLEL AND MONOCHROMATIC BEAMS FOR DETERMINING THE COMPOSITION OF PSEUDOBINARY ALLOYS BY X-RAY-FLUORESCENCE

A simple X-ray fluorescence method using nearly parallel and monochromatic beams is analyzed and discussed in connection with the determination of the alloy fraction in pseudobinary A1-x B x C solid solutions. Applications to optoelectronic materials are considered. The reliability of the method has been analyzed and discussed for both bulk and thin film samples. Errors due to small angular divergence in the accepted beam are seen to be neglibile. Deviations from a symmetrical alignment of the sample can strongly influence the measured fluorescence intensity. The experimental analysis of this effect can be used for a perfect symmetrical orientation of thick samples. The measurement of the fluorescence intensity as a function of the glancing angle can give both thickness and composition in solid-solution thin-film samples. The contributions of the fluorescence radiation excited by the characteristic X-ray lines of atoms within the substrate is shown to be important in thin epitaxial layers. An approximate formula for calculating these contributions is given and discussed in the light of experimental results. Bulk crystals and thin-film samples, vapourphase grown Cd1-x Zn x S solid solutions, have been used for experiments in which the Zn K α radiation excited by a Mo K α primary beam was measured. © 1979 Springer-Verlag.