MEASUREMENT OF COMPOSITION OF THIN-FILMS OBTAINED BY SPUTTERING USING RADIOISOTOPE EXCITED X-RAY-FLUORESCENCE

An energy-dispersive x-ray fluorescence (EDXRF) apparatus using a radioisotope source with a secondary target (Am-241-Mo) and a Si(Li) x-ray spectrometer was used to measure the Cu, Sr and Bi contents of thin (100 mug cm-2) films sputtered on to MgO. The results were found to be in excellent agreement with those obtained from MeV Rutherford backscattering (RBS) analysis of the same films. The calibration of the EDXRF apparatus was done by measuring x-ray intensities excited in thin sol-gel films of known Cu, Sr and Bi content, as given by the accurately known chemical solutions from which the sol-gel films were prepared. The experimental calibration constants were in excellent agreement with the theoretical values calculated using a thin-film equation, which assumes that characteristic x-ray absorption and secondary excitation are negligible, and the published atomic x-ray data.