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The luminescence properties of ZnO:Al nanopowders obtained by sol-gel and vaporization-condensation methods
|Larisa Grigorjeva 1, Donats Millers 1, Claude J. Monty 2, Jules KOUAM 2, Kamel Djessas 3|
1. Institute of Solid State Physics, University of Latvia, 8 Kengaraga, Riga LV-1063, Latvia
ZnO is attractive material for many practical applications. Doping with Al enhances luminescecne of this mateiral. ZnO nanopowders (undoped and Al doped) were prepared by sol-gell method (SG). The SG made powders were used as substrates for vaporisation-condensation process (VC) using the SPVD (Solar Physical Vapor Deposition) method. The luminescence spectra were measured in spectral range 1.55 eV-3.75 eV under 266 nm pulsed laser excitation (pulse duration 10 ns). The luminescence decay process was analysed in time range 2ns - 1ms with time resolution 2 ns. SEM, FTIR, XRD were used for samples characterisation. The luminescence spectra for SG and VC nanopowders are different mainly in the range 2.6 -3.1 eV. The defects responsible for luminescence within this region disappeared during VP process. However both sets of ZnO:Al samples (SG and VP) show defect state luminescence intensity larger than that fresulting from excitons recombination. The well-resolved excitons luminescence band observed in VC nanopowder indicate that in these powders there are regions with defect free ZnO structure. The defect luminescence decay kinetics shows an initial fast (<10 ns) decay followed by a slower one (ms range). This slow decay of luminescence might be due to electron tunneling. Possible processes responsible for luminescence observed will be discussed.
Presentation: Invited oral at E-MRS Fall Meeting 2006, Symposium C, by Larisa Grigorjeva
See On-line Journal of E-MRS Fall Meeting 2006
Submitted: 2006-05-17 09:28 Revised: 2009-06-07 00:44