Radiation-Induced Recombination and Trapping Centers in Germanium. I. The Nature of the Recombination Process

Abstract

Extensive measurements on irradiated germanium indicate that previous analyses of the recombination process are incorrect. A model which explains the observations in both $n$- and $p$-type material is presented. According to this model, the recombination level lies 0.36 ev above the valence band in gamma-irradiated $n$-type germanium. Presumably due to the extensive perturbation caused by neutron irradiation, the level lies slightly lower in neutron-irradiated material. Trapping levels which are not present in antimony-doped germanium occur in arsenic-doped material ∼0.17 ev above the valence band. Other trapping levels are observed only in high-resistivity antimony-doped samples. It has not been possible, from the data presented, to determine the values of hole and electron capture cross sections associated with the recombination level; however, the ratio $\frac{{\sigma }_p}{{\sigma }_n}$ has been determined: Its value is ∼1000.