Browsing by Subject "D. optical properties"

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    Dependence of the photoluminescence of Tl2InGaS4 layered crystal on temperature and excitation intensity
    (Pergamon Press, 1998) Gasanly, N. M.; Serpengüzel, A.; Gürlü, O.; Aydınlı, A.; Yılmaz, I.
    The emission band spectra of Tl2InGaS4 layered crystals were investigated in the 10-120 K temperature range and in the 540-860 nm wavelength range using photoluminescence (PL). The peak energy position of the emission band is located at 1.754 eV (707 nm) at 10 K. The emission band has a half-width of 0.28 eV and an asymmetric Gaussian lineshape. The increase of the half-width of the emission band, the blue shift of the emission band peak energy and the quenching of the PL with increasing temperature is explained using the configuration coordinate model. The blue shift of the emission band peak energy and the sublinear increase of the emission band intensity with increasing excitation intensity is explained using the inhomogenously spaced donor-acceptor pair recombination model. © 1998 Elsevier Science Ltd. All rights reserved.
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    Low-temperature photoluminescence spectra of TlInxGa1-xS2 layer mixed crystals
    (Pergamon Press, 1995) Allakhverdiev, K. R.; Gasanly, N. M.; Aydınlı, Atilla
    Low-temperature photoluminescence spectra of TlInS2, TlIn0.95Ga0.05S2 and TlIn0.8Ga0.2S2 layer crystals were studied in the temperature range 14-220 K. The temperature dependencies of bands 2.374 eV (A), 2.570 eV (E) and 2.576 eV (F) for TlInS2 are interpreted by supposing that the crystal undergoes structural phase transitions. Band A is considered to come from a donor-acceptor recombination channel. © 1995.
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    Visible photoluminescence from low temperature deposited hydrogenated amorphous silicon nitride
    (Pergamon Press, 1996) Aydınlı, A.; Serpengüzel, A.; Vardar, D.
    Hydrogenated amorphous silicon nitride (a-SiNx:H) samples have been prepared by plasma enhanced chemical vapor deposition (PECVD) using a mixture of silane (SiH4), nitrogen and ammonia (NH3). Most films exhibit visible photoluminescence (PL) and some emit strong PL after annealing. While films grown without NH3 exhibit PL in the deep red, those grown with NH3 show PL in the green. The PL properties of these films with no oxygen (O) content are similar to those of silicon oxide (SiOx) films and porous Si. Using infrared and X-ray Photoelectron Spectroscopy, we suggest that PL from a-SiNx:H films originate from Si clusters which form during PECVD and crystallize upon annealing. We propose that the presence of O is not necessary for efficient PL.
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    Visible photoluminescence from SiOx films grown by low temperature plasma enhanced chemical vapor deposition
    (Pergamon Press, 1995) Timofeev, F. N.; Aydınlı, Atilla; Ellialtioglu, R.; Turkoglu, K.; Gure, M.; Mikhailov, V. N.; Lavrova, O. A.
    a-SiOx films of varying stoichiometry have been prepared by low temperature plasma enhanced chemical vapor deposition. The majority of films showed photoluminescence (PL) and films prepared in a narrow range of gas flows exhibited much stronger PL after annealing. Peak PL energies ranging from the ultraviolet to the near infrared have been observed. PL, infrared and X-ray diffraction on selected samples indicate formation of Si clusters in the films. The effects of annealing on the PL properties of the films have been found to depend on initial stoichiometry of the films. © 1995.