Identification of native defects around grain boundary in Pr-doped ZnO bicrystal using electron energy loss spectroscopy and first-principles calculations

Native defects and Pr dopant around grain boundaries in Pr-doped and undoped ZnO bicrystals were investigated by electron energy loss spectroscopy (EELS) with a focus on the relationship with the current–voltage characteristics. The Pr-doped bicrystal exhibited a nonlinear current–voltage characteristic, whereas the undoped bicrystal shows an ohmic characteristic. In the Pr-doped bicrystal, Pr was found to be present within 8nm around the grain boundary. EELS investigation of native defects combined with first-principles calculations indicated the presence of zinc vacancies in the vicinity of the Pr-doped grain boundary. The formation of zinc vacancies is considered to be the origin of the nonlinear current–voltage characteristic.