Complexes of self-interstitials with oxygen atoms in germanium

Interactions of germanium self-interstitials with interstitial oxygen atoms in Ge crystals have been studied by combining experimental and theoretical methods. Self-interstitials were created in oxygen-rich Ge crystals by irradiation with MeV electrons at 80K, and I–O-related complexes were studied by means of infrared absorption spectroscopy, while the density functional theory was used to model structures, local vibrational modes and electronic properties of IO and I2O centers. It is argued that two absorption lines at 674 and 602cm−1, which develop upon annealing of irradiated Ge:O crystals in the temperature range 180–220K, are related to IO complexes, while another set of bands at 713 and 803cm−1 is related to I2O. Those assignments are supported by the comparison with the calculated local vibrational modes of the defects.