A comparative study of photo-, cathodo- and ionoluminescence of GaN nanowires implanted with rare earth ions

GaN nanowires (NWs) implanted with Europium, Praseodymium and Erbium ions were analysed by Photoluminescence (PL), Cathodoluminescence (CL) and Ionoluminescence (IL). The red 5D0 → 7F2 and 3P0 → 3F2 luminescence of the Eu3+ (4f6) and Pr3+ (4f2) ions, respectively, was optically activated after the lattice damage was recovered by thermal annealing. On the contrary, for the case of the erbium implanted NWs no intra-4f11 transitions were identified in the visible and infra-red spectral range. Besides the lanthanide luminescence, the heat treated GaN NWs exhibit the band edge recombination and a deep level emission in the yellow spectral range when the samples are excited by photons, electrons and protons with energies of 3.8 eV, 5.0 keV and 2.0 MeV, respectively. At RT, the dependence of GaN NW luminescence intensity with the illumination/irradiation time was analysed using PL, CL and IL. The effects of the different excitation mechanisms are discussed to explain the observation that the broad emission bands suffer a luminescence quenching for the GaN NWs irradiated with energetic particles and photons. The influence of the irradiation on the optical properties of the GaN NWs is discussed and models for the recombination processes are established.