The influence of low fluence high‐energy ion irradiation on the modification of the ZnO surface structure and optical properties has been studied. ZnO samples of various orientations, namely, c‐plane (0001), a‐plane (11–20) and m‐plane (10–10), have been implanted with 30‐MeV Au ions with fluences ranging from 5 × 109 to 5 × 1011 cm−2. Rutherford backscattering spectrometry in the channelling mode (RBS‐C) and Raman spectroscopy has shown the distinct damage accumulation in the irradiated surface layer about 1 μm depending on the ZnO facet being to larger extent evidenced in the m‐plane ZnO. Contrary, the a‐plane ZnO has been exhibited the lowest Zn disorder. Using atomic force microscopy (AFM), a complex morphology was detected on the irradiated samples containing grains and exhibiting increased roughness, both growing with the Au implantation fluence mainly in m‐plane ZnO. Positron annihilation spectroscopy (PAS) has shown distinct defect accumulation at the Au‐ion fluence of 5 × 1011 cm−2, where RBS‐C and Raman spectroscopy indicated sudden disorder increase in the irradiated layers, probably the creation of more complex clusters of Zn and O vacancies 4VZn + 8VO initiated in connection with an overlap of individual ion impacts. Photoluminescence measurements have shown a distinct near‐band‐edge (NBE) luminescence, developing with the increasing Au‐ion fluence in various ZnO orientations. The m‐plane ZnO had the most progressively suppressed NBE in comparison with the other orientations.

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Nanopillars of ZnO were implanted with Au-400keV ions at various ion fluences from 1 × 1E15 cm-2 to 1 × 1E16 cm-2 and subsequently annealed at 750 °C for 15 minutes in order to reduce the implantation damage and to support Au nanoparticle aggregation. It was found that implantation-induced effects and thermal effects influence the Au nanoparticle coalescence as well as the quality of the ZnO nanopillars. RBS showed the broader Au-depth profiles than it was theoretically predicted. The implantation at the higher fluences induced the morphology modification of the nanopillar layer evidenced by RBS and SEM. An indirect evidence of this effect was given by optical ellipsometry due to gradual refractive index changes in the ZnO nanopillars with the increased Au-ion fluence. Optical characterization of the Au-implanted and annealed nanopillars performed by means of photoluminescence (PL) and diffuse-reflectance spectroscopy (DRS) evidenced the surface plasmon resonance (SPR) activity of the embedded Au nanoparticles. The SPR-enhanced scattering and PL emission observed in the spectral range 500–650 nm are ascribed to Au nanoparticles or more complex Au-clusters. In addition, the ellipsometry measurements of extinction coefficient are found to corroborate well results from DRS, both indicating increase of SPR effect with the increase of Au-ion fluence and after the post-annealing.