Behavior of N -Type Ge Exposed to Highly Energetic Radiation

Measurements of the irradiation response and subsequent recovery during annealing of the conductivity, Hall coefficient, and Hall mobility of $n$-type germanium are presented here. The samples were bombarded at 80\ifmmode^\circ\else\textdegree\fi{}K with 5- to 45-MeV electrons and with high-energy gamma rays, which produce significant amounts of damage via photoneutron reactions. The electron bombardment rate apparently had no effect on the initial irradiation response. However, Cu impurities were found to produce strong effects in both the irradiation and annealing behavior. A significant amount of annealing was observed between 80 and 300\ifmmode^\circ\else\textdegree\fi{}K, which is evidently a manifestation of the defects formed by highly energetic radiation. Between 300 and 400\ifmmode^\circ\else\textdegree\fi{}K impurities play an important role in the annealing, since the annealing appears to be controlled by the original chemical donor. An interpretation of the results based on a model involving migration of only a single defect is found to be inadequate.