单晶硅衬底材料中的消光衍射

在经典衍射理论中,Si(2 0 0 ) ,Si(2 2 2 )等4 n+2面的反射是消光的,但在单晶硅或硅基材料中,常发现Si(2 0 0 ) ,Si(2 2 2 )的衍射.考虑非谐效应和电子云反对称分布的贡献,分别计算了Si(2 0 0 ) ,Si(2 2 2 )消光衍射的相对强度,并用XRD测试手段进行了验证.结果表明,理论与实验值基本符合.在室温下,Si(2 0 0 ) ,Si(2 2 2 )衍射主要是因为反对称的电子云分布所致.同时,强调了Si(2 0 0 ) ,Si(2 2 2 )衍射在XRD分析中的应用

Forbidden Reflections in the Single Crystal Si Substrate

In the conventional theory of X-ray diffraction, th e 4n 2 reflections are forbidden such as Si(200) and Si(222) reflection.Howe ver,these sorts of the forbidden reflections are observed in single crystal Si o r Si-based materials.When the anharmonic contribution to the temperature factor and the antisymmetric bonding charge distribution are taken into account,the re lative intensities of the forbidden (200) and (222) reflections are calculated,r espectively.It is found that the calculated values are in agreement with the obs erved values by using XRD technique.The results also indicate that forbidden (20 0) and (222) reflections can occur mainly for the antisymmetric charge density d istribution at room temperature.And the applications of forbidden reflections ar e emphasized in the XRD analysis.