利用自主研发的热壁低压化学气相沉积(HWLPCVD)系统，在5.08cm(２英寸)4°偏轴4H-SiC衬底上生长4H-SiC同质外延膜。讨论了4H-SiC同质外延层中的两种扩展缺陷——彗星缺陷和胡萝卜缺陷，研究了这两种缺陷的起源与消除方法。研究发现采用化学机械抛光(CMP)方法可以有效去除扩展缺陷，提高外延膜的质量。另外，提高衬底质量和优化生长条件也可以消除这两种扩展缺陷。

4H-SiC epilayers were grown on 4°offaxis 4H-SiC substrates by employing a novel homemade horizontal hot wall low pressure chemical vapour deposition (HWLPCVD) system. The two extended defectscomet defects and carrot defects were investigated, and the origin and elimination of the extended defects were studied for the first time. Analytical results show that chemical mechanical polishing (CMP) is an effective way to eliminate the extended defects, and the quality of the epitaxial layers can be improved through this process. Improving the quality of the substrates and changing the growth condition can control the extended defects as well.