Vibration modes of oxygen dimers in germanium

Absorption in the infrared region of the spectrum was studied for both the as-grown Ge crystals and the Ge crystals irradiated with fast electrons (wi th subsequent heat treatment); the crystals were preliminarily enriched wit h O-16 or O-18 isotopes. The vibrational absorption bands observed in Ge an d peaked at 780, 818, and 857 cm(-1) are attributed to complexes composed o f two atoms (dimers) of O-16, whereas the bands at 741, 776, and 811 cm(-1) are attributed to complexes of O-18 atoms. It is established that electron irradiation of Ge crystals at temperatures near 295 K with subsequent heat treatment at 120-250 degreesC brings about an increase in the intensities of bands peaked at 780 and 818 cm(-1). The band peaked at 857 cm(-1) does n ot change its intensity under irradiation and, by analogy with Si, is ident ified with another configuration of oxygen dimers in Ge. The bonding energy of dimers responsible for the bands peaked at 780 and 818 cm(-1) is estima ted at 0.35-0.4 eV. (C) 2001 MAIK "Nauka/Interperiodica".