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The luminescence properties of ZnO:Al nanopowders obtained by sol-gel and vaporization-condensation methods

Larisa Grigorjeva 1Donats Millers 1Claude J. Monty 2Jules KOUAM 2Kamel Djessas 3

1. Institute of Solid State Physics, University of Latvia, 8 Kengaraga, Riga LV-1063, Latvia
2. CNRS laboratoire Procedes, Materiaux et Energie solaire (PROMES), BP5 Odeillo, Font-Romeu 66120, France
3. Perpingnan University, Perpingam Cedex, Perpignan 66860, France


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.


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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