Anomalous dependence of photoluminescence properties on composition x in Cd1-x Mnx Ga2S4 mixed crystals

Photoluminescence spectra of Cd1–x Mnx Ga2S4 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. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)