Enhanced formation of thermal donors in irradiated germanium: local vibrational mode spectroscopy

Oxygen-rich Ge samples were bombarded with fast electrons (E=4 MeV) at 80 d egrees C and subjected to isochronal (100-340 degrees C) and isothermal (35 0 degrees C) annealing. Infrared absorption spectra were measured at room t emperature. Preliminary irradiation of the samples is found to strongly enh ance the development of the absorption bands in the range 600 to 780 cm(-1) when the Ge < Sb,O > crystals are heated to 350 degrees C. The bands are a ssigned to local vibrational modes of thermal donors. It is inferred from t he annealing studies that a radiation-induced complex with the local vibrat ional modes at about 770-780 cm(-1) is probably responsible for the enhance d growth of the thermal donors. Oxygen dimers are proposed as such a comple x. (C) 1999 American Institute of Physics. [S1063-7826(99)00211-2].