Anomalous dependence of photoluminescence properties on composition x in Cd1-xMnxGa2S4 mixed crystals

Photoluminescence spectra of Cd1-xMnxGa2S4 mixed crystals were investigated in the composition region of 0.00≤x≤1.00 and in the temperature region of 6 to 300 K. The photoluminescence spectrum of CdGa2S4 (x=0.00) showed two emission bands at 594 nm (2.09 eV) and 460 nm (2.70 eV), which were attributed to be due to donor-acceptor pair recombination. The same feature of these bands was also observed for the crystals doped with 5 mol% Mn, excepting a slightly red shift and a decreasing of the halfwidth of the emission band in the longer wavelength region. For the crystals in the composition region of x≤0.67, only the emission band in the longer wavelength region were observed. The photoluminescence spectra of MnGa2S4 (x=1.00) showed a broad emission band 675 nm (1.838 eV), which is different from that of CdGa2S4. The relative intensity of the main emission band increased in the composition region of 0.00≤x≤0.67 with increasing x while decreased in the region of 0.90≤x≤1.00. The anomalous composition dependence was connected with an occurrence of a miscibility gap of the crystal structure in that region. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)