α—SiC晶体中的位错

用腐蚀法和X射线形貌术研究了α-SiC晶体中的位错。所用的腐蚀剂为熔融氢氧化钾。证实了尖底蚀坑与位错的一一对应关系。由于0001]方向的螺型位错的Burgers矢量比刃型位错的Burgers矢量大得多,故可从蚀坑的深浅来判别螺型位错和刃型位错。给出了蚀坑形状和多型体晶体结构的对应关系。研究了表面生长蜷线的形态与SiC晶体中的位错及位错运动的关系。X射线形貌图显示了α-SiC晶体中相当数量的位错处于基面C面上。生长位错从晶体“根部”成核并随着晶体生长前沿的向前推进而延伸,因而位错线的方向常常沿101O]和1120]方向。将腐蚀法和X射线形貌术结合起来才能全面显示α-SiC晶体中的位错。 关键词：

DISLOCATIONS IN α-SILICON CARBIDE SINGLE CRYSTAL

The dislocations in cc-SiC single crystal are studied by means of etching method and X-ray topographic method. The etchant used is the fused alkali hydroxide. The one-to-one correspondence between the etch pits with sharp bottom and the dislocations are confirmed. Because of the Burgers vector of the screw dislocations in 0001] direction are much larger than that of the edge dislocations, one can distinguish the screw dislocations from the edge dislocations according to the depth of etch pits. The correspondent relation between the shape of etch pits and the crystal structure of polytype is given. The relationships between the pattern of growth spiral on surface and the dislocations as well as the movement of dislocations are studied. X-ray topography shows that a lot of dislocations in cc-SiC are on the base plane (C plane). The growth dislocations nucleate at the crystal root and extend along the direction of crystal growth passing through the whole crystal in the crystal growth process, so the dislocation lines are always along the 1010] and 1120] direction. The dislocations in cc-SiC crystal can be observed completely only when both the etching method and X-ray topographic method are employed.