4H-SiC晶体中的层错研究

采用物理气相传输法(PVT法)在4英寸(1英寸=25.4 mm)偏<11¯20>方向4°的4H-SiC籽晶的C面生长4H-SiC晶体。用熔融氢氧化钾腐蚀4H-SiC晶体, 并利用光学显微镜研究了晶体中的堆垛层错缺陷的形貌特征和生长过程中氮掺杂对4H-SiC晶体中堆垛层错缺陷的影响。结果显示, 4H-SiC晶片表面的基平面位错缺陷的连线对应于晶体中的堆垛层错, 并且该连线的方向平行于<1¯100>方向。相对于非故意氮掺杂生长的4H-SiC晶体, 氮掺杂生长的4H-SiC晶体中堆垛层错显著偏多。然而, 在氮掺杂生长的4H-SiC晶体的小面区域, 虽然氮浓度高于其他非小面区域, 但是该小面区域并没有堆垛层错缺陷存在, 推测这主要是由于4H-SiC晶体小面区域特有的晶体生长习性导致的。

Stacking Faults in 4H-SiC Single Crystal

Thenitrogen doped and unintentional nitrogen doped 4H-SiC single crystals were grown by PVT method on the C-terminated 4H seeds offcut by 4° from the c-face towards the <11¯20> axis, respectively. Optical microscope was used to investigate the characteristic of stacking fault defects and the effects of nitrogen doped onstacking fault defects in 4H-SiC single crystals etched by molten KOH etching. The result shows that the lines of the basal plane dislocation defect of the 4H-SiC wafer surface are corresponding to stacking fault defects in 4H-SiC single crystals, and the direction of the lines is parallel to <1¯100>. There are more stacking fault defects in 4H-SiC single crystals doped with nitrogen than that of unintentional nitrogen doped 4H-SiC single crystals. This phenomenon is consistent with published literatures in which high concentrations of nitrogen caused the formation of stacking fault defects in 4H-SiC single crystals. However, there is no stacking fault defect in the facet area for nitrogen doped 4H-SiC single crystals, although the nitrogen concentration in the facet area is higher than that in the other area, which is presumably due to specific crystal growth habit in the facet area of 4H-SiC single crystal.