Berlin 2008 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 49: ZnO: Optical properties

HL 49.2: Vortrag

Donnerstag, 28. Februar 2008, 11:00–11:15, ER 164

Influence of dielectric capping on the phololuminescence spectrum of ZnO nanowires nanowires — •Jan Richters, Tobias Voss, Ilja Rückmann, and Jürgen Gutowski — Institute of Solid State Physics, University of Bremen, P.O. Box 330440, D-28334 Bremen

Due to the large surface-to-volume ratio and the photon confinement, ZnO nanowires are expected to be good candidates for applications in nanoscale optoelectronics in the blue spectral region and for sensors. For many devices, the nanowires need to be embedded in organic or inorganic materials or functionalized with surfactants. It is important to understand the influence of these treatments on the optical and electronic properties of ZnO nanowires to optimize their use in such devices. We report on room-temperature and low-temperature photoluminescence studies of ZnO nanowires embedded in organic and inorganic dielectrics. For this, we investigate ZnO nanowires embedded in various polymers as well as aluminum/ZnO nanowire core-shell structures. The capping in general results in a more pronounced surface exciton band. Additionally, a decreased relative intensity of the green deep-level emission with respect to the near band-edge emission can be observed. These effects scale with the dielectric constants of the amorphous dielectrics. Capping with a dielectric influences the surface states as well as the band bending at the semiconductor surface. We present a model to explain the changes of the relative intensities of the photoluminescence bands.