Photoluminescence of ZnS x Se 1-x epilayers and single crystals

Photoluminescence properties of ZnS(x)Se(1-x) (x is in the range of 0 to 1) epilayers on GaP substrates and of corresponding ZnS(x)Se(1-x) single crystals are examined. The samples have been grown by vapor phase iodine transport. The blue emission bands of the single crystals are quenched in the epilayers. Comparison of the luminescence properties of ZnSe crystals grown by sublimation without iodine clearly shows that iodine creates deep recombination levels of high concentration. By simple sublimation without transporting agent and subsequent annealing in Ga and Zn deep emission bands are suppressed in favor of blue edge emission. Differences in the spectra obtained by the use of source materials from two manufacturers are assigned to unidentified background impurities.