Transmission Electron Microscopy of Sublimation-Grown GaN Single Crystal and GaN Homoepitaxial Film

Abstract
A GaN film with nominal thickness of 0.6 µ m was homoepitaxially deposited on a sublimation-grown GaN single-crystal substrate. An electron-transparent area of 10 µ m×10 µ m prepared by focused Ga ion beam machining was examined by transmission electron microscopy. In addition to the dislocations on the basal plane of the wurtzite unit cell, another type of dislocation, near pure edge in character and aligned close to the c-axis direction, was found in the GaN substrate crystal. Neither type of dislocation threaded to the top surface. Dislocation-free growth was achieved in the GaN homoepitaxial film.