Problems and Trends in X-Ray Detector Design for Microanalysis

Abstract

This paper presents some of the problems and trends associated with silicon and germanium x-ray detectors for microanalysis as seen from the manufacturer’s point of view. The crystal and field-effect transistor FET comprise a transducer which is sensitive enough to detect charge of the order of 20–30 electron-hole pairs. At the same time, it must be fixed accurately in confined space in a hostile radiation environment and must be maintained at cryogenic temperatures without its magnetic, electrical, and mechanical properties in any way influencing the performance of the microscope to which it is interfaced. Such considerations impose severe constrictions on the design of these detectors, and many compromises must be made. For example, the demand for the low-energy efficiency afforded by a truly windowless (WL) detector is being relaxed more and more in favor of competing considerations such as protection from light, as in the ultra-thin window detector (UTW), and cross contamination and simplicity, as in the atmospheric pressure-supporting window detector (ATW).