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采用1000W卤钨灯作为光源,对GaN外延膜在KOH溶液中进行化学腐蚀,以显示晶体位错.采用扫描电子显微镜、原子力显微镜观察位错密度及表面形貌,得到了清晰的腐蚀图形.提出了腐蚀机理,光照激发位错处产生电子空穴对,加速位错处的腐蚀速率.GaN表面出现了大量的六角腐蚀坑(位错露头).优化了KOH溶液的腐蚀条件.
A 1000W tungsten halogen lamp was used as a light source to chemically etch the GaN epitaxial film in KOH solution to show crystal dislocation.The clear corrosion pattern was obtained by scanning electron microscopy and atomic force microscopy after dislocation density and surface morphology were observed. The corrosion mechanism is that the light excites the electron-hole pairs at the dislocations and accelerates the corrosion rate at the dislocations. A large number of hexagonal corrosion pits (dislocation outcrops) appear on the GaN surface. The corrosion conditions of the KOH solution are optimized.