High Resolution Site-Selective Studies of Erbium-Centers in GaN and GaN:Mg.

Abstract

AbstractIn this work the high resolution optical spectroscopy is used in order to determine the positions of the Stark split 4I15/2, 4I11/2 and 4I9/2 energy levels of Er3+ in GaN and GaN:Mg. Photoluminescence and photoluminescence excitation spectra were measured at energies corresponding to the 4I15/2→4I9/2 and 4I15/2→4I11/2 absorption transitions. Low Er implant doses were applied to reduce the number of possible defects. In undoped GaN only a single Er-center was observed and no influence of Mg doping on the energy level splittings of this center in GaN:Mg was found. Numerical analysis based on point charge model was used to calculate parameters of the local crystal field (CF) acting on Er3+ ions. The splittings of the 4I9/2 and 4I11/2 energy levels were calculated in weak CF approach and good agreement with experimental results was obtained. The calculations confirmed that the symmetry of the erbium center in hexagonal GaN is C3v.