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Excitation intensity and temperature-dependent photoluminescence and optical absorption in Tl4Ga3InSe8 layered crystals

Photoluminescence (PL) spectra of Tl4Ga3InSe8 layered crystals grown by Bridgman method have been studied in the wavelength region of 600-750 nm and in the temperature range of 17-68 K. A broad PL band centered at 652 nun (1.90 eV) was observed at T = 17 K. Variations of emission band has been studied as a function of excitation laser intensity in the 0.13 to 55.73 mW cm(-2) range. Radiative transitions from donor level located at 0.19 eV below the bottom of conduction band to shallow acceptor level located at 0.03 eV above the top of the valence band were suggested to be responsible for the observed PL band. From X-ray powder diffraction and optical absorption study, the parameters of monoclinic unit cell and the energy of indirect band gap were determined, respectively. (C) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.