Spectral response of multi-element silicon x-ray detectors

An x-ray spectrometer combining multi-element silicon detectors and multi-channel integrated circuit pulse-processing electronics is being developed for low noise, high count rate synchrotron x-ray fluorescence applications. This paper reports on the issues surrounding the use of highly segmented silicon detectors for x-ray spectroscopy. Several different detector geometries were modeled using commercially available device simulation software, and selected geometries were fabricated using planar processing techniques on high resistivity silicon. The detectors were characterized using a 5 mu m diameter 8.5 keV x-ray beam, and Fe-55 and Cd-109 radioisotope sources. Spectral background, anomalous peaks, peak-to-background and charge sharing between adjacent detector elements were studied. The measured x-ray spectral responses are interpreted with respect to the device simulations. These measurements bring to light the effects of detector design, detector processing techniques and detector materials properties on the spectral response of the detector.