BANDGAP BOWING AND SPONTANEOUS ORDERING IN ZNSEXTE1-X

We present the results of experimental investigations on bandgap bowin g and spontaneous ordering in MOVPE grown ZnSexTe1-x. The bowing param eter of b = 1.40 +/- 0.05eV found from different optical measurements on our epilayers is slightly larger than values found earlier from bul k material, indicating the possibility of spontaneous ordering in our samples. Ab-initio calculations for Zn2SeTe in the ordered CuAu- and C uPt-structures lean support to this possibility. In fact X-ray measure ments performed on our samples with x = 0.39 and x = 0.54 show peaks, forbidden in the zincblende structure, which give evidence for spontan eous ordering in the CuPt structure.