Mössbauer-type photoluminescence spectra of irradiated germamum

Abstract A Mossbauer-type structure has been observed in the 15°K spectra of germanium crystals irradiated at room temperature by Co60 γ-rays and 700 keV electrons. The spectra consist of an intense band peaking at 0.688 eV accompanied by mainly TA-phonon-assisted lower energy sidebands. The transition producing the luminescence is believed to be the annihilation of an exciton bound to a defect center by forces of shorter range than coulombic attraction. The dependence of the new spectra upon irradiation temperature and certain sample characteristics indicate that the center contains both primary defect(s) and an unknown impurity.