Recombination Domain Instability in High Energy Electron Irradiated Germanium

When a bar of n -type germanium (1∼2 Ω-cm) is irradiated with a total flux of about 10 15 ∼10 16 electrons/cm 2 at 8.5 MeV, domains of high electric field in the irradiated crystal appear at a high field above 350 V/cm and 77 K. At sufficiently high electric fields, current-valtage characteristics, estimated by observing an instantaneous current density and a time constant associated with the trapping of hot electrons at defect centers, have a voltage-controlled differential negative resistance region. So the high field domain is formed by the build-up of the space charge boundaries. The velocity of moving domain ranged from 10 5 cm/sec to 2 × 10 6 cm/sec, depending upon the light intensity.