Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2014)
    Nanomaterials Tuesday Sessions
       Session NM-TuE

Paper NM-TuE5
Spatial Mapping of Exciton Lifetimes in Single Zno Nanowires

Tuesday, December 9, 2014, 7:00 pm, Room Hau

Session: Nanomaterials Characterization & Reactivity II
Presenter: Frank Güell, Universitat de Barcelona
Authors: F. Güell, Universitat de Barcelona
J.S. Reparaz, Institut Catala de Nanotecnologia
G. Callsen, Technische Universität Berlin
M.R. Wagner, Institut Catala de Nanotecnologia
A. Hoffmann, Technische Universität Berlin
J.R. Morante, Institut de Recerca en Energia de Catalunya
Correspondent: Click to Email

The quest for novel semiconductor materials with improved optoelectronic performance has triggered intense research activities to exploit the great diversity of effects offered by low dimensional systems. In this work, we demonstrate that the recombination dynamics of excitons in ZnO nanowires can be well understood within the concept of optical nanocavities. We investigate the spatial distribution of the lifetimes of the near-band-edge and bound-exciton emissions in single ZnO nanowires with different dimensions by means of temperature dependent and time-resolved spectroscopy. We demonstrate that the lifetime of the excitons is systematically reduced by 30% at the tips of the nanowires with respect to their maximum value at the center, which originates from the combined effect of the cavity-like properties of these nanostructures with the Purcell effect. In addition, show that the model of Rashba and Gurgenishvili is valid even at the nanoscale, i.e. the lifetime of the bound excitons is proportional to the localization energy (Eloc) to the power of 3/2. This result provides a means to understand the spatial dependence of the lifetimes of the near-band-edge emission (NBE), which is not intuitive due to their spatially extended nature. Finally, the temperature dependence of the photoluminescence and lifetimes of the excitons in single nanowires is also briefly discussed in comparison to bulk ZnO samples.