Photoluminescence spectra of Zn1−xCdxAl2S4 (0.0⩽x⩽0.2;0.8⩽x⩽1.0) single crystals

The photoluminescence spectra as well as the lattice constants and band gaps for the mixed single crystals Zn1−xCdxAl2S4 with 0.0⩽x⩽0.2 and 0.8⩽x⩽1.0 grown by the chemical transport reaction method were investigated. The Zn1−xCdxAl2S4 crystals were a cubic spinel phase α in the range of 0.0⩽x⩽0.2 and a defect chalcopyrite in the range of 0.8⩽x⩽1.0, and showed a miscibility range from x=0.2 to x=0.8 in the composition dependence of the lattice constants and band gaps. We observed two emission bands consisting of a strong blue emission band and a weak broad emission band due to donor-acceptor pair recombinations in the crystals with a cubic spinel and a defect chalcopyrite structure. These emission bands showed a different behavior in their temperature and composition dependence. An energy band scheme for the radiative mechanism of the Zn1−xCdxAl2S4 was proposed on the basis of our experimental results along with the measurements of photoinduced current transient spectroscopy and thermoluminescence.