A Simple Procedure to Check the Spectral Response of an EDX Detector

Abstract

Recent advances in semiconductor detection systems have extended the accessible energy range down to 100 eV and allow the identification of light elements in energy dispersive X-ray spectra. A quantitative analysis on the basis of the K-line intensities of these elements, or of the low energy line intensities of heavier elements, is getting now strongly dependent on the spectral response of the detector in the region below 1 keV. The spectral response is not time constant but changes due to the growth of contamination layers on the detector window and/or the detector crystal. The periodic record of the spectrum of a freshly cleaved Si surface provides a simple check of the response function. As an example, spectra are given for a detector with ice contamination and for the same detector after removal of this layer. The sensitivity of the check can be increased dividing the spectrum by the detector window transmission. In a similar way, spectra can be corrected regarding the transmission of contamination layers before quantification as shown for boron nitride.