Carrier Trapping in High-Purity Germanium

As part of a continuing effort to improve crystal growing control and the yield of high resolution coaxial detectors made from high-purity Germanium, Photothermal Ionization Spectroscopy, Resistivity and Hall measurements versus temperature and carrier lifetime measurements on detector diodes, have been combined, in an attempt to reveal the nature and origin of the trapping. PTIS points to the possible role of oxygen in creating trapping centers. The deep level structure of high-purity Ge, especially after thermal treatment, is too complex to make it possible to attribute trapping to one particular deep level, as e.g. the divacancy hydrogen (80 meV) complex. Preferential trapping of electrons and holes has been observed.