Electron Radiation Damage in Cadmium-Selenide Crystals at Liquid-Helium Temperature

CdSe crystals grown by the vapor-deposition method show a cathodoluminescence spectrum at 5^∘{}K with peaks at 1.34 and 1.74 eV. Under electron bombardment, above an energy threshold of 320 keV, a new emission band at about 1.1 eV is produced. An isochronal annealing experiment shows the annihilation of the damage in one step at 62^∘{}K. Previous experiments at 77^∘{}K showed a threshold at 250 keV for the generation of a fluorescence band at 0.99 eV. The threshold observed at 320 keV is assigned to the displacement of a cadmium atom with an energy transferred of 8.1 eV. The threshold at 250 keV is assigned to the displacement of the selenium atom with an energy transferred of 8.6 eV.