Synthesis and fluorescence properties of a nanoisland-structured SiOx/CuxO composite

摘要

A nanoisland-structured SiOx (x <= 2)/CuxO (x <= 2) composite was prepared from a Cu-deposited Si wafer by electrochemical anodization in a hydrofluoric acid (HF) and ferric nitrate (Fe(NO3)3) electrolyte. The surface of the nanoisland comprised Cu, Cu oxides, Si nanoparticles and Si oxides. The distribution of elemental Cu on the surface was uniform. Cracks and native Cu-oxides in the deposited Cu layer are the two main factors for the formation of the nanoisland-structured surface. Different from the single red photoluminescence (PL) band emitted from the electrochemical anodized bare Si wafer, a dualvisible PL band with comparable intensities at red and blue ranges was observed. The red PL quenching did not occur in this Cu-ion-doped nanostructured Si due to the different distribution areas of Cu+ and the red PL centre. The red PL originates due to oxygen defects in the band gap of Si nanoparticles/Si oxides; the blue PL is the consequence of the band-to-band transitions between 3d(10) and 3d(9)4s(1) of Cu+ ions and the intra d -> d band transition of Cu2+ ions in the interstitial vacancies of Si oxides. Compared with the electrochemical anodized bare Si sample with a single PL band, the nanoisland-structured SiOx/CuxO composite emitting a dual-PL-band is more promising for fabricating white light emitters.