title: Enhanced near band edge luminescence of Ti/ZnO nanorod heterostructures due to the surface diffusion of Ti.
abstract: Information on the mechanistic differences in the luminescence properties of Ti/ZnO nanorods (NRs) has been obtained through the preparation of heterostructures by (a) varying the thickness of Ti from 1 nm to 20 nm keeping the substrate temperature at 400 °C, (b) varying the substrate temperature from room temperature (RT) to 500 °C while keeping the metal thickness constant at 10 nm and (c) annealing the RT Ti sputtered NRs at temperatures of 400 °C and 500 °C. The photoluminescence (PL) spectra show that the near band edge luminescence of ZnO in the ultraviolet (UV) region is enhanced as the thickness of Ti increases up to 5 nm and, thereafter, it falls. Sputtering of Ti on ZnO NRs at RT does not cause any UV enhancement but when sputtered at and above 400 °C, the UV intensity is enhanced. Annealing of RT Ti sputtered NRs at and above 400 °C also results in the enhancement of the UV peak, although with a lesser magnitude. Analysis of the PL results, supported by X-ray diffraction, field emission scanning electron microscopy, elemental mapping, high resolution transmission electron microscopy, Fourier transform infrared spectroscopy and electrical I-V measurement results, show a clear indication that the surface diffusion of Ti causes a reduction in the surface defects.
authors.affiliation: Department of Solid State Physics, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
authors.forename: Moumita
authors.initials: M
authors.lastname: Mahanti
authors.forename: Tushar
authors.initials: T
authors.lastname: Ghosh
authors.forename: Durga
authors.initials: D
authors.lastname: Basak
mesh_terms: D004058:Diffusion; D043942:Nanotubes / Q000737:chemistry* / Q000648:ultrastructure; D013056:Spectrophotometry, Ultraviolet; D013499:Surface Properties; D013696:Temperature; D014025:Titanium / Q000737:chemistry*; D015034:Zinc Oxide / Q000737:chemistry*
chemical_list: D014025:Titanium; D015034:Zinc Oxide