Below and above bandgap excited photoluminescence in Tl4InGa3S8 layered single crystals


Goksen K., Gasanly N.

JOURNAL OF PHYSICS-CONDENSED MATTER, cilt.19, 2007 (SCI İndekslerine Giren Dergi) identifier identifier

Özet

Photoluminescence (PL) spectra of Tl4InGa3S8 layered single crystals grown by the Bridgman method have been studied in the 550-710 nm wavelength and 80 300 K temperature ranges with below bandgap excitation (lambda(exc) = 532 nm), and in the 420-600 nm wavelength and 30-300 K temperature ranges with above bandgap excitation (lambda(exc) = 325 nm). The broad emission bands centered at 580 nm (2.14 eV) and 496 nm (2.49 eV) were observed at T = 80 and 30 K for below and above bandgap excitation processes, respectively. Variations in emission spectra have been studied as a function of excitation laser intensity in the 10.3-429.7 mWcm(-2) range for below bandgap excitation. Radiative transitions from the donor levels located at 0.02 and 0.37 eV below the bottom of the conduction band to the deep acceptor level located at 0.20 eV above the top of the valence band were proposed to be responsible for the observed PL bands. From x-ray powder diffraction and EDS analysis, the monoclinic unit cell parameters and compositional parameters, respectively, were determined.