Structural properties of nitrogen-ion implanted ZnO nanorods

The structural deformation of nitrogen-ion implanted ZnO nanorods was investigated. Vertically aligned ZnO nanorods were synthesized on Al ₂O₃ substrates, both with and without buffer layers, using catalyst-free metal organic chemical vapor deposition (MOCVD). Nitrogen ions, with energy of 120 keV and two different beam fluxes; 1 × 10¹⁶ and 1 × 10 particles/cm², were implanted on the vertically aligned ZnO nanorods. Field-emission scanning electron microscopy (FE-SEM) measurements revealed the shape of the ZnO nanorods was little changed using the nitrogen-ion implantation with a total beam flux of 1 × 10¹⁶ particles/cm², while the nanorods were seriously deformed with a total beam flux of 1 × 10¹⁷ particles/cm². X-ray diffraction measurements demonstrated that, compared to untouched ZnO nanorods, the both nanorods had ordered wurtzite structures, but no detectable disorder was observed from the nanorods exposed for a total nitrogen-ion beam flux of 1 × 10¹⁶ particles/cm², while substantial structural distortion was observed in the nitrogen-implanted nanorods with a total beam flux of 1 × 10¹⁷ particles/cm². Field-emission transmission tunneling microscopy (FE-TEM) measurements on the nanorods with the nitrogen-ion beam flux of 1 × 10¹⁶ particles/cm² showed substantial structural deformation due to the ion implantation. Our observation strongly suggested that nitrogen-ion implantation could be a solution for the hole-doping of ZnO nanorods.