通过改变AlN形核层的生长温度分别在Si(111)衬底上生长了两个GaN样品,并对GaN外延材料表面的六角形缺陷进行了分析研究。通过显微镜和扫描电镜(SEM)观测发现,AlN形核层在高温下生长时,GaN材料表面会产生大量六角形缺陷。通过电子能谱(EDS)分析得出GaN六角形缺陷中含有大量的Si元素以及少量的Ga和Al元素,其中Si元素从Si衬底中高温扩散而来。在降低AlN形核层的生长温度后,GaN材料表面的六角形缺陷随之消失。表明AlN形核层在较低的温度下生长时可以有效地抑制Si衬底表面Si原子的扩散,减少外延层中由于衬底Si反扩散引起的缺陷。 Two GaN samples were grown on a Si (111) substrate by changing the growth temperature of the AlN nucleation layer, and the hexagonal defects on the surface of the GaN epitaxial material were analyzed. Microscopic and scanning electron microscopy (SEM) observations showed that a large amount of hexagonal defects were produced on the surface of GaN when AlN nucleation layer was grown at high temperature. EDS analysis shows that the GaN hexagonal defect contains a large amount of Si and a small amount of Ga and Al, in which Si diffuses from the Si substrate at high temperature. After reducing the growth temperature of the AlN nucleation layer, the hexagonal defects on the surface of the GaN material disappear. It shows that AlN nucleation layer can effectively inhibit the diffusion of Si atoms on the surface of Si substrate and reduce the defects in the epitaxial layer due to the back diffusion of Si substrate at lower temperature.