The Characterization of N Interstitials and Dangling Bond Point Defects on Ion-Implanted GaN Nanowires Studied by Photoluminescence and X-Ray Absorption Spectroscopy

摘要

Photoluminescence and X-ray absorption spectroscopy (XAS) measurement were used to characterize the near-band edge (NBE) emission intensity and electronic structure of as-implanted GaN nanowires (NWs) that had been implanted with Eu ions to different fluences. The N K- and Ga L_3-edge of total electron yield XAS spectra showed the formation of N interstitials (N_i) and dangling bond (N_(db)) point defects and the formation of metallic Ga layers on the surface of NWs. X-ray diffraction, Ga K- and L_3-edge of total fluorescence yield XAS spectra consistently revealed the wurtzite structure of the as-implanted NWs up to the highest fluence. The ratio of absorption intensity found in sp~3 and sp~2 environment and the NBE intensity were strongly affected by the implantation. It is suggested that the decrease of NBE intensity was closely related to the change from sp~3 to sp~2 environment. The absorption intensity ratio between the as-grown and as-implanted samples of N_(db) and N_i was directly proportional to the fluences indicating that these defects are preferentially formed during implantation.