Experimental investigation of the annealing processes in germanium irradiated at 77 K with 14 MeV neutrons

Abstract n- and p-type Germanium at 77 °K has been irradiated by 14 MeV-neutrons and subsequently annealed. The results are compared with those obtained from reactor irradiated materials. The observed changes of Hall-constant and electrical resistivity of n- and p-type Ge can be de-scribed by the disordered regions model. In p-Ge the disordered regions decay by isochronal annealing between 77 °K and 230 °K. This process is superposed by the process of the creating and the decay of a type of defect that has also been observed after electron irradation. After reactor-neutrons irradiation n-Ge shows a reverse annealing between 100 °K and 150 °K. In this temperature interval no steady state annealing effects have been observed after 14 MeV-neutrons. It is suggested that during each annealing stage vacancies diffuse out of the defect zones and are trapped by small defect clusters in reactor irradiated n-Ge. In 14 MeV irradiated material nearly no such small clusters are present, so the vacancies diffuse until they are retrapped by the disordered regions. The process of back diffusion can be measured. It obeys an exponential law. Between 150 °K and 230 °K after either type of irradiation a reverse annealing takes place. It is suggested that in this annealing interval the defects of the disordered regions become divacancies.