Spatially resolved luminescence properties of ZnO tetrapods
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ZnO tetrapods were prepared by Zn-vapour deposition at 740 °C in Argon and subsequent oxidation in air for 1–30 min. The photoluminescence (PL) and cathodoluminescence (CL) spectra were measured from ZnO particles collected at various distances from the Zn source representing decreasing dimensions. The ZnO tetrapods showed a green emission centred at 516 nm (2.40 eV) band and the exciton emission at 387 nm (3.20 eV). The measured data suggested that the green emission is strongly increased for particle sizes below 500 nm, whereas the exciton emission is dominant for particle size larger than 500 nm. Spatially resolved CL-measurement on individual tetrapod legs showed, that the green emission increases with decreasing ZnO leg diameter. To our knowledge, the local CL spectroscopic measurements were correlated with the dimensions of the individual ZnO tetrapods for the first time.
KeywordsGreen Emission Sampling Distance Exciton Emission Strong Exciton Emission Short Wavelength Device
The authors are grateful to E. Völkl for the technical assistance on the CL-measurements. Financial support of the German Science Foundation (DFG) and the University of Erlangen-Nuremberg is gratefully acknowledged. C.R. Rambo thanks CNPq-Brazil for the financial support.