Probing Threading Dislocations in a Micrometer-Thick GaN Film by High-Voltage Scanning Transmission Electron Microscopy

Dislocations in a semiconductor crystal, such as gallium nitride (GaN), degrade its optical and electrical properties. To detect and characterize lattice defects in a thick crystalline specimen which can be regarded as bulk, high-voltage electron microscopy (HVEM) is a powerful technique The penetration of relativistic electrons depends on imaging conditions as well as materials, and quantitative unified views regarding the maximum usable thickness have not been obtained. Recent interest in crystal defects in semiconductor devices has drawn renewed attention to visualizing microstructures in an extremely thick specimen by HVEM. The authors focused on high-voltage scanning transmission electron microscopy (STEM) as a tool for imaging precipitates and dislocations in micrometer-thick crystals In this study, we examined quantitative assessment of the maximum usable thickness of GaN crystal with high-density threading dislocations (TDs) using HV-STEM