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采用条形Al掩模在Si(111)衬底上进行了GaN薄膜侧向外延的研究。结果显示,当掩模条垂直于Si衬底[11-2]方向,也即GaN[10-10]方向时,GaN无法通过侧向生长合并得到表面平整的薄膜;当掩模条平行于Si衬底[11-2]方向,也即GaN[10-10]方向时,GaN侧向外延速度较快,有利于合并得到平整的薄膜。同时,研究表明,升高温度和降低生长气压都有利于侧向生长。通过优化生长工艺,在条形Al掩模Si(111)衬底上得到了连续完整的GaN薄膜。原子力显微镜测试显示,窗口区域生长的GaN薄膜位错密度约为1×109/cm2,而侧向生长的GaN薄膜位错密度降低到了5×107/cm2以下。
The lateral epitaxial growth of GaN films was investigated on a Si (111) substrate by using a strip Al mask. The results show that when the mask is perpendicular to the direction of the Si substrate [11-2], that is, the GaN [10-10] direction, GaN can not be combined by lateral growth to obtain a planarized thin film. When the mask is parallel to the Si When the direction of the substrate [11-2], that is, the direction of GaN [10-10], the lateral epitaxial speed of GaN is faster, which is advantageous for the formation of a flattened film. At the same time, studies show that increasing the temperature and reducing the growth pressure are conducive to lateral growth. By optimizing the growth process, a continuous and complete GaN film was obtained on a strip-shaped Al mask Si (111) substrate. Atomic force microscopy showed that the dislocation density of the GaN film grown in the window region was about 1 × 10 9 / cm 2, while the dislocation density of the laterally grown GaN film was reduced to less than 5 × 10 7 / cm 2.