LOW-ENERGY X-RAY RESPONSE OF GE DETECTORS WITH AMORPHOUS-GE ENTRANCE CONTACTS

The low energy x-ray response of Ge detectors with amorphous Ge entrance contacts has been evaluated. The spectral background due to near contact incomplete charge collection was found to consist of two components: a low level component which is insensitive to applied voltage and a high level step-like component which is voltage dependent. At high operating voltages, the high level component can be completely suppressed, resulting in background levels which are much lower than those previously observed using Ge detectors with Pd surface barrier or B ion implanted contacts, and which also compare favorably to those obtained with Si(Li) x-ray detectors. The response of these detectors to Fe-55 and 1.77 keV x-rays is shown. A qualitative explanation of the origins of the observed background components is presented.