Light-Sensitive Defect Formation by Electron and Neutron Irradiation of n- and p-type Germanium near 80 °K

Abstract

Measurements of the electrical conductivities and Hall coefficients for neutron-irradiated (76 °K) and electron-irradiated (80 °K) n- and p-type Ge have been made as a function of illumination and isochronal annealing (80–700 °K) to investigate the characteristics of neutron-produced defect clusters in Ge. For p-type Ge there is no effect of illumination immediately following either electron or neutron irradiation but such a dependence is observed after the 140 °K annealing period. This illumination dependence anneals out between 200 and 240 °K. For n-type Ge the effect of illumination on the electrical properties is significantly larger following neutron irradiation than following electron irradiation. Eighty percent of the neutron-produced illumination sensitivity anneals out between 200 and 400 °K. The electrical conductivity in neutron-irradiated n-type Ge is near a degradation maximum after annealing to 240 °K, whereas it is essentially recovered to the preirradiation value in p-type Ge. Furthermore, reverse effects in neutron-irradiated n-type Ge for annealing between 150 and 220 °K contrast with a 100–200 °K recovery after electron irradiation. These results are interpreted as evidence for the neutron formation of high-resistivity p-type defect clusters which increase their p-type character upon annealing to ∼ 200 °K, and recover by vacancy liberation between ∼ 200 and 450 °K. Annealing effects between 400 and 600 °K are interpreted to involve defect-impurity complexes in both electron- and neutron-irradiated n-type Ge.