Electron-Bombardment Induced Recombination Centers in Germanium

Abstract

The rate of change of minority carrier lifetime in germanium crystals bombarded by 1-Mev electrons has been studied experimentally as a function of the initial resistivity of the material. Analysis of the data leads to the conclusion that a single recombination center controls lifetime in both n- and p-type material, that this level is located at either 0.21±0.005 ev from the conduction band or else at 0.26±0.005 ev from the valence band, and that the ratio of the cross section for capture of minority holes is 18 times the cross section for capture of minority electrons. The absolute value of the hole capture cross section is 4.5×10−15 cm2 if one uses the best available data for the probability of producing a Frenkel defect by a 1-Mev electron. This large value is compared to the findings of other authors in similar experiments.