Encapsulation of high-purity germanium detectors

The encapsulation of high purity germanium detectors is very desirable in order to increase their versatility and reliability. However, rapid and extensive degradation is seen for all detectors made from detector grade crystals which are encapsulated in a simple vacuum. Extensive studies have shown that the cause of this degradation is hydrogen adsorption on the detector surface. There it causes the formation of a strong p+ inversion layer which in turn shunts the detector junction. Reliable encapsulation is shown to be achievable by the use of hydrogen-free germanium crystals.