Vacancies and interstitial atoms in e(-)-irradiated germanium

High purity Ge wafers have been irradiated at low temperatures with MeV ele ctrons and have subsequently been investigated by x-ray diffraction methods . The intensity of the Huang diffuse scattering shows that a high concentra tion of defects (>10(19) cm(-3)) can be frozen in at 4 K. A large fraction of the defects is stabilized in the form of close Frenkel pairs which are c haracterized by the nearly perfect cancellation of the long range displacem ent fields of the interstitial atom and the vacancy. We discuss the absolut e size of these displacements as well as the introduction rate of the defec ts, which is of the order of Sigma = 3 cm(-1). The high defect introduction rates are at variance to the results of electrical and optical investigati ons and indicate that these methods detect only a few percent of the total defect concentration which is produced and frozen in at 4 K. The consequenc es for the understanding of the defect production in Ge and for the assumpt ion of an athermal migration of interstitial atoms are discussed in close r elation to similar results for Si. In addition, we discuss the differences between the defect patterns observed after 4 K irradiation to those observe d after room-temperature irradiations and the thermally activated defect re actions up to the final annealing at 600 K. (C) 1999 American Institute of Physics. [S0021-8979(99)04407-2].