Mn_xCd_(1-x)In_2Te_4晶体生长研究

Crystal growth of MMn_xCd_(1-x)In_2Te_4

采用Bridgman法生长四元稀磁化合物半导体Mn0 .2 2Cd0 .78In2 Te4晶体。当晶体生长到预定长度时 ,淬火得到固液界面。采用光学显微镜、扫描电镜、X射线衍射仪、ISIS能谱仪以及Leica定量金相分析仪研究了晶体中出现的界面形态、相的形貌和数量以及沿生长方向的相析出规律 ,并进行了相成分分析。研究发现 ,淬火得到的Mn0 .2 2 Cd0 .78In2 Te4晶体中存在两个界面 ,其中一个为固液相变界面 ,另一个为由α + β两相区发展到单相 β区时的转变界面 ,二者相对于生长初始端均为凹形 ;α+ β两相区中 ,β相以条状、花状和近似圆片状形式存在 ,其中条状 β相多分布在晶界处 ;越接近生长初始端 ,花状和近似圆片状β相越小 ,条状 β相越细 ,它们的含量越少 ;X射线衍射图谱表明 ,β相为黄铜矿结构 ,α相为面心立方结构。

One diluted magnetic semiconductor of Mn x Cd 1- x In 2Te 4 ( x =0.22) ingot has been grown by Bridgman method. Quenched interfaces were obtained by shutting off the electricity power of the furnace after the ingot had grown for the predetermined length. Using an optical microscope, a scanning electron microscope, an X ray powder diffraction spectrometer, an ISIS energy dispersive spectroscope and a Leica quantitative optical microscope, the quenched interfaces and microstructure were observed, the change of the β phase content along the longitudinal axis of the ingot was determined quantitatively, and the phase formation process was analyzed. There are two interfaces in the ingot, one is the liquid/solid interface and another the transformation interface for α+β two phase region to single β phase region. The morphology of the β phase was plate, flower or near round. Among them, β plates always lie in the grain boundaries. In the place near to the starting tip of the ingot, the β plates are thinner, their amount is smaller, and less flower β blocks exist. The lattice structure of β phase is chalcopyrite, while that of α phase is fcc.