Exploration of TEM sample preparation for GaN dislocations based on in situ FIB-SEM

Dislocation is a major defect limiting the performance and lifetime of GaN devices. Investigating the microscopic structure of GaN dislocations at the atomic scale by transmission electron microscope (TEM) is beneficial to deepen the understanding of the dislocation formation mechanism and provide guidance for the growth of GaN with low dislocation density. However, prepare a high-quality TEM sample of GaN for dislocation analysis is challenging. This work explores the cross-sectional and planar TEM sample preparation techniques for GaN using a focused ion beam (FIB)-SEM dual-beam system. The microscopic atomic structures of dislocation defects in GaN are successfully characterized. This novel sample preparation technique is also applicable to the fabrication of TEM planar samples of other bulk materials.