SPECTRAL RESPONSE OF MULTIELEMENT SILICON X-RAY-DETECTORS

An x-ray spectrometer combining multi-element silicon detectors and mu lti-channel integrated circuit pulse-processing electronics is being d eveloped 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 di fferent detector geometries were modeled using commercially available device simulation software, and selected geometries were fabricated us ing planar processing techniques on high resistivity silicon. The dete ctors were characterized using a 5 mu m diameter 8.5 keV x-ray beam, a nd Fe-55 and Cd-109 radioisotope sources. Spectral background, anomalo us peaks, peak-to-background and charge sharing between adjacent detec tor elements were studied. The measured x-ray spectral responses are i nterpreted with respect to the device simulations. These measurements bring to light the effects of detector design, detector processing tec hniques and detector materials properties on the spectral response of the detector.