title: Influence of helium-ion bombardment on the optical properties of ZnO nanorods/p-GaN light-emitting diodes.
abstract: Light-emitting diodes (LEDs) based on zinc oxide (ZnO) nanorods grown by vapor-liquid-solid catalytic growth method were irradiated with 2-MeV helium (He+) ions. The fabricated LEDs were irradiated with fluencies of approximately 2 × 1013 ions/cm2 and approximately 4 × 1013 ions/cm2. Scanning electron microscopy images showed that the morphology of the irradiated samples is not changed. The as-grown and He+-irradiated LEDs showed rectifying behavior with the same I-V characteristics. Photoluminescence (PL) measurements showed that there is a blue shift of approximately 0.0347 and 0.082 eV in the near-band emission (free exciton) and green emission of the irradiated ZnO nanorods, respectively. It was also observed that the PL intensity of the near-band emission was decreased after irradiation of the samples. The electroluminescence (EL) measurements of the fabricated LEDs showed that there is a blue shift of 0.125 eV in the broad green emission after irradiation and the EL intensity of violet emission approximately centered at 398 nm nearly disappeared after irradiations. The color-rendering properties show a small decrease in the color-rendering indices of 3% after 2 MeV He+ ions irradiation.
authors.affiliation: Department of Science and Technology (ITN), Campus Norrköping, Linköping University, 60174 Norrköping, Sweden. nhalvi@gmail.com.
authors.forename: Naveed Ul Hassan
authors.initials: NU
authors.lastname: Alvi
authors.forename: Sajjad
authors.initials: S
authors.lastname: Hussain
authors.forename: Jen
authors.initials: J
authors.lastname: Jensen
authors.forename: Omer
authors.initials: O
authors.lastname: Nur
authors.forename: Magnus
authors.initials: M
authors.lastname: Willander