“Enhancement of surface morphology and optical properties of nanocolumnar ZnO films”

J.OROZCO; V.DONDERIS; L. C. DAMONTE; J.CEMBRERO; M.A.HERNÁNDEZ-FENOLLOSA

SUPERLATTICES AND MICROSTRUCTURES

Elsevier

Año: 2007 vol. 42 p. 461 - 467

0749-6036

Nanocolumnar ZnO films were prepared by electrodeposition (ED) on polycrystalline conductive FTO covered glass. After deposition the samples were annealed in oxidizing or reducing atmosphere, at temperatures between 100 to 500ºC, in order to follow the evolution of optical properties and morphology. The optical properties of these films were studied by means of photoluminescence spectroscopy (PL) and the morphology by scanning electron microscopy (SEM). Films annealed at 300oC exhibit the higher ultraviolet emission peak, originating from exciton transitions and a green band related to deep-level emission and centered at 500 nm shows a drastical increase at 500ºC. These results are independent of the annealing atmosphere. An increase of coalescence is also observed after annealing at 500ºC. These results are explained taking into account the contribution of different point defects.