Atom probe tomography evaporation behavior of C-axis GaN nanowires: Crystallographic, stoichiometric, and detection efficiency aspects

摘要: The field evaporation behavior of c-axis GaN nanowires was explored in two different laser-pulsed atom probe tomography (APT) instruments. Transmission electron microscopy imaging before and after analysis used to assist reconstructing the data assess observed behavior. It found that ionic species exhibited preferential locations for related underlying crystal structure which evaporated from these dependent on pulsed laser energy. Additionally, overall stoichiometry measured by APT significantly correlated with energy pulses. At lowest energies, apparent composition nitrogen-rich, while higher energies resulted measurements predominantly gallium compositions. percent ions detected (detection efficiency) specimens be considerably below shown other materials, even produced expected Ga:N ratio. variation low detection efficiency appear a result Ga between pulses at neutral N2 energies. All behaviors are tied formation nitrogen-nitrogen bonds tip surface, occurred under all conditions. Similar therefore materials where anionic readily form strong diatomic bond.