A Study on Crystal Defects in Epitaxial GaN Film by High-Order Weak-Beam Electron Microscopy

Various crystal defects in epitaxial GaN film were studied by high-order bright-field and dark-field electron microscopy. The results revealed that the film is composed of small grains in nano-meter scale. Distinct shapes of the grain boundaries and a great number of threading dislocations were shown in the experimental g/3g weak-beam images. Diffraction contrast analysis verified that the majority of threading dislocations is 1/3<11 2 0> edge dislocation. A unique (11 2 0) planar defect was observed in the specimen. The defect was identified to have a similar structure to the incipient 1/3[11 2 0] edge dislocation.