基于同步辐射白光形貌术和X射线迹线法的6H-SiC单晶结构缺陷研究

目的]SiC材料结构缺陷的检测和控制是实现材料应用的关键环节,因此本文对6H-SiC单晶中的结构缺陷进行研究。方法]采用同步辐射白光形貌术观察6H-SiC单晶中的基本螺位错和基平面弯曲,并利用X射线迹线法模拟基本螺位错的形貌和基平面弯曲后衍射斑点的形状。结果]6H-SiC单晶中的典型结构缺陷之一为基本螺位错,它的形貌特征为白色的圆斑;由于热弹应力的存在,6H-SiC单晶在生长过程中容易发生基平面弯曲,结果导致衍射斑点的形状发生改变。结论]同步辐射白光形貌术和X射线迹线法可以用于检测6H-SiC单晶结构缺陷;样品的基本螺位错密度为1.56×10~4/cm~2,基平面弯曲半径近似为1m。

Investigation on Structural Defects in 6H-SiC Single Crystal by Synchrotron Radiation White-Beam Topography and X-ray Tracing Method

Objective] A key step to realize the application of SiC materials is the detection and control of structural defects in 6H-SiC single crystals, which was studied herein.Methods] Elementary screw dislocations and basal plane bending were observed by means of synchrotron radiation white-beam topography.In the meantime, the morphology of an elementary screw dislocation and the shape of diffraction beam in case of basal plane bending were simulated by X-ray tracing method.Results] One of typical structural defects in 6H-SiC single crystals is the elementary screw dislocation, which exhibits the characteristic of white dot in synchrotron radiation image.Due to the existence of thermo-elastic stress during the 6H-SiC crystal growth, the basal plane is easily bended.As a result, the shape of diffraction beam is deformed.Conclusion] Synchrotron radiation white-beam topography and X-ray tracing method can be used to examine structural defects in 6H-SiC single crystals.At present work, the density of elementary screw dislocation is 1.56×10⁴/cm² and the radius of basal plane bending is approximately 1 meter.