Fullerene Irradiation Leads to Track Formation Enclosing Nitrogen Bubbles in GaN Material

Gallium nitride was irradiated with fullerene projectiles having an electronic stoppingpower above the threshold needed to promote ion track formation. The structural andchemical changes induced by fullerene irradiation were studied though TransmissionElectron Microscopy (TEM). High resolution TEM inquiries were performed to identifythe structural order along the ion tracks and the strain induced in the latticeneighboring the ion tracks. The TEM investigation pointed out local amorphizationinside the whole tracks and High Resolution TEM studies in the track peripheryevidence local stress in the wurtzite structure. Chemical investigations were carried outby STEM - Electron Energy Loss Spectroscopy (EELS) to describe the chemical orderin the neighboring and inside the ion path. Chemical profiles plotted across ion tracksindicate that the Ga/N stoichiometry is essentially maintained in the core track, anoxidation in the ion track periphery was also detected at the surface. Furthermore, thenitrogen k near-edge fine structure investigation reveals the encapsulation of nitrogenbubbles inside the ion tracks.