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提出了一种确定GaN外延薄膜中位错种类的方法。通过化学试剂对GaN薄膜表面进行选择性腐蚀,并用X射线衍射仪(XRD)及原子力显微镜(AFM)对腐蚀前后的薄膜进行了表征,确立了GaN薄膜表面的蚀坑形貌与位错类型之间的对应关系。XRD测试结果表明,GaN薄膜中的位错密度并不随着腐蚀时间延长而发生变化。采用AFM对蚀坑形貌进行深度剖析,发现了四种不同的位错蚀坑:倒六角锥型蚀坑、倒六角平台型蚀坑、倒双六角平台型蚀坑以及混合型蚀坑。进一步研究表明,这四种不同的位错蚀坑分别对应于四种不同的位错种类,所有蚀坑基本都可以沿着这四种腐蚀路线演化而来。同时用扫描电镜(SEM)观察到的蚀坑形貌与AFM测试结果基本一致。
A method to determine the types of dislocations in GaN epitaxial films is proposed. The surface of GaN film was selectively etched by chemical reagents. The films before and after etching were characterized by X-ray diffraction (XRD) and atomic force microscope (AFM), and the morphology of pits and dislocation of GaN films were established The correspondence between. XRD results show that the dislocation density in the GaN film does not change with the increase of the etching time. Using AFM to analyze the morphology of pits, four different dislocation pits were found: inverted hexagonal pits, inverted hexagonal pits, inverted double hexagonal pits and mixed pits. Further studies have shown that these four different dislocation pits correspond to four different types of dislocation, respectively, and all the pits can basically evolve along these four corrosion paths. At the same time, the morphology of pits observed by scanning electron microscopy (SEM) was basically consistent with AFM test results.