Luminescence of pure and doped ZnO films synthesised by thermal annealing on GaSb single crystals

ZnO films were grown onto GaSb substrates by metallic Zn thermal evaporation and subsequent oxidation by annealing in atmospheric conditions. The evaporation times ranged from 20 to 80 s. The oxidation process was carried out at temperatures close to 410 ∘C although other temperatures were also checked. In addition to pure ZnO, rare-earth-doped ZnO films have also been grown by this technique, Eu and Ho oxides were selected due to their application as red phosphors and upconversion. The luminescence properties of both pure and doped films have been studied. The samples were characterized by means of micro Raman, micro photoluminescence and cathodoluminescence spectroscopies, in order to obtain local information about the crystal quality of the films and also regarding to the presence of non-desirable phases, impurities, etc. The samples present good luminescence emission; the spectra show an intense UV emission, with a very low band in the visible. Some defect related bands are observed. Moreover, SbOx phases seem to be formed for some specific growth conditions.