A divacancy model was proposed which explained a number of experimental observations of Ge exposed to a flow of accelerated electrons at 77K. The model explained the absence of photo-conduction associated with the photo-excitation of infra-red absorption bands at 0.44 and 0.52eV (corresponding to divacancies), the difference in the values of activation energy for divacancy energy levels determined by optical and electrical methods and the existence of the limiting position of the Fermi level in the forbidden gap in the case of irradiation using high radiation fluxes.

On the Model of Divacancies in Germanium. N.D.Dolidze, B.E.Tsekvava: Physics of the Solid State, 2002, 44[11], 2034-8