Interaction of self-interstitials with oxygen-related defects in electron-irradiated Ge crystals

Electrically active defects induced by irradiation with MeV electrons in oxygen-rich n-type Ge crystals have been studied by means of capacitance transient techniques. Transformation of the defects upon post-irradiation isochronal and isothermal anneals has also been investigated. It is argued that radiation-induced defects with energy levels at 62 (E62) and 80 meV (E80) below the conduction band edge are associated with complexes of Ge self-interstitials with oxygen-related defects. These complexes are formed upon annealing of electron-irradiated samples at T>50 °C and anneal out at temperatures higher than 140 °C. The activation energy of formation of the dominant E62 defect has been found to be 0.80 eV.