TRANSMISSION ELECTRON-MICROSCOPY OF SUBLIMATION-GROWN GAN SINGLE-CRYSTAL AND GAN HOMOEPITAXIAL FILM

A GaN film with nominal thickness of 0.6 mu m was homoepitaxially depo sited on a sublimation-grown GaN single-crystal substrate. An electron -transparent area of 10 mu m x 10 mu m prepared by focused Ga ion beam machining was examined by transmission electron microscopy. In additi on to the dislocations on the basal plane of the wurtzite unit cell, a nother type of dislocation, near pure edge in character and aligned cl ose to the c-axis direction, was found in the GaN substrate crystal. N either type of dislocation threaded to the top surface. Dislocation-fr ee growth was achieved in the GaN homoepitaxial film.