Excitation intensity- and temperature-dependent photoluminescence in layered structured Tl2GaInSe2S2 crystals

Photoluminescence spectra of Tl2GaInSe2S2 layered crystals have been registered in the temperature range of 17-62 K and in the wavelength region of 525-690 nm. A broad visible photoluminescence band centered at 590 nm (2.10 eV) was observed at T 17 K. Variation of emission band has been studied as a function of laser excitation intensity in the 0.1-55.7 mW cm(-2) range. The analysis of the spectra reveals that the peak energy position changes with excitation intensity (blue shift). The radiative transitions from moderately deep donor level to shallow acceptor level were suggested to be responsible for the observed band. From X-ray powder diffraction study, the parameters of monoclinic unit cell of Tl2GaInSe2S2 were determined. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4792499]