6H-SiC单晶中的微管和小角度晶界

利用透射偏光显微术、同步辐射X射线形貌术、高分辨X射线衍射方法对6H-SiC(0001)晶片中的微管和小角度晶界等缺陷进行了研究.实验发现,在透射偏光显微镜下,微管通常呈现为蝴蝶形,这是由于微管周围存在着应力场,且应力分布不均匀,当线偏振光在通过微管周围区域时传播速度不同造成的.从X射线背反射同步辐射形貌像得到晶片中微管的Burgers矢量大小在2c到10c之间.从晶片00012衍射的双晶衍射摇摆曲线可以看出,晶片的中间大部分区域质量很好,双晶衍射峰为单峰且半峰宽很窄,一般为35"左右.在外围区域双晶衍射峰的半峰宽变宽,有些区域还会出现衍射峰的分裂,这说明外围区域有嵌镶块结构存在.

Micropipe and Low-angle Grain Boundaries in 6H-SiC Single Crystal

Micropipes and low-angle boundaries in 6H-SiC (0001) wafer are determined by transmission polarized light microscopy, synchrotron X-ray topography and high-resolution X-ray diffraction method, respectively. Micropipes are usually highlighted as butterfly shape observed by optical microscopy in the transmission polarizing light mode, which is considered to be composed of the distribution of the birefringence formed by the internal strain around the micropipes. The magnitude of Burgers vector of hollow-core screw dislocations in 6H-SiC wafer varies from 2c to 10c obtained by X-ray synchrotron topograph in back-reflection geometry recorded from (0001) plane. High-resolution X-ray diffraction rocking curve of 00012 diffraction shows that single diffraction peak with full width at half maximum of 35 arcsec in the central regions, which indicates high crystal quality. The split-peaks in the peripheral regions indicate the existence of subgrains slightly misoriented to each other.