TiO2 nanotube layers: Dose effects during nitrogen doping by ion implantation

TiO2 nanotubes were produced by self-organized electrochemical oxidation of Ti. The tubes were N-ion implanted at two nominal fluencies, 1 × 1015 and 1 × 1016 ions/cm2. Implantation was carried out into amorphous and crystalline (anatase) tubes. lectrochemical, SEM and XRD measurements show successful doping at a dose of 1 × 1016 ions/cm2, however the ion implantation process causes strong structural alterations. Amorphous tubes show a disintegration of the morphological integrity, while anatase tubes are ‘amorphized’. This amorphization leads to a decrease of photoresponse in the UV range, but the N-doping results in a strong sub-band gap response.