Twins in CdMnTe single crystals grown by Bridgman method

Cd_1-xMn_xTe (x=0.2, CdMnTe) crystal was grown by the vertical Bridgman method, which exhibits a pure zincblende structure in the whole ingot. The major defect, twins, which is fatal to CdMnTe crystal, was analyzed with scanning electron microscopy (SEM), X-ray energy disperse spectroscopy (XEDS) and optic microscopy on the chemical etching surface. The twins observed in the as-grown ingot are mainly lamellar ones, which lie on the {111} faces from the first-to-freeze region of the ingot and run parallel to the growth axis of the ingot. Coherent twins with {115}_t-{111} _h orientations when indexed with respect to both the twin and host orientations, are often found to be terminated by {110}_t-{114} _h lateral twins. Te inclusions with about 20 μm in width are observed to preferentially decorate the lamellar twin boundaries. The origin of the twins, relating to the growth twin and the phase transformation twin, is also discussed in this paper.