Massive icing of a high-purity Ge EDS detector with an ultrathin window

Abstract

High Purity Germanium (HPGe) EDS detectors are now commercially available. Their main advantage over the commonly used Si(Li) EDS detectors is the increased absorption at higher energies due to the higher mass density of germanium. As a result, in modern medium voltage TEMs the K-shells of even heavy elements can be utilized for analytical electron microscopy. In addition, in order to increase the detector performance in the low energy range, an ultrathin window is used instead of a beryllium window. While detectors with a beryllium window are baked, evacuated and then sealed during the manufacturing process (the detecting crystal, therefore, being in a closed environment), our detector with an ultrathin window is not sealed and when in use, is constantly pumped by the microscope vacuum system. While not in use, the detector is retracted behind a valve, at which time it is not pumped.