Photoluminescence engineering in polycrystalline ZnO and ZnO-based compounds

• Published in: AIMS materials science 2016-01, Vol.3 (2), p.508-524
• Main Authors: Markevich, Iryna, Stara, Tetyana, Khomenkova, Larysa, Kushnirenko, Volodymyr, Borkovska, Lyudmyla
• Format: Article
• Language: English
• Subjects: ceramics; defects; doping; photoluminescence; photoluminescence excitation; rear earth; screen-printing; ZnMgO; ZnMgO–TiO2; ZnO
• ISSN: 2372-0484
• DOI: 10.3934/matersci.2016.2.508

The results of the investigations of photoluminescence (PL) in ZnO and ZnO-based composite materials are presented. The PL and PL excitation (PLE) spectra of undoped and doped with I group elements or rear earth ions ZnO polycrystalline films, ZnO, Zn1–xMgxO and ZnMgO–TiO2 ceramics were studied. The structural properties of the samples were investigated with X-ray diffraction. Polycrystalline films were prepared by a screen-printing method and annealed at TS = 500–1000 °C. The films annealed at TS < 800 °C exhibited intense UV emission, whereas defect-related one appeared at 800 °C and enhanced with increasing TS. Improvement of the PL and structural characteristics of ZnO films due to Li-doping were achieved. The PL bands caused by Sm and Ho ions were observed under ZnO band-to-band excitation. In the PL spectra of ZnO and Zn1–xMgxO ceramics, two types of PL bands were separated: i) the bands, whose spectral positions were not influenced by the Mg content (green Cu-related as well as self-activated orange and red ones); ii) the bands, spectral positions of which exhibited some blueshift with increasing Mg content (orange Li- and Ag-related and self-activated green ones). In the PL spectra of ZnMgO–TiO2 composites, an intense red emission was found to appear in addition to the broad blue-orange band inherent in ZnMgO alloy. The red emission was ascribed to Mg2TiO4 inclusions in ZnMgO matrix.