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Intense Red Photoluminescence Emission of Sol–Gel‐Derived Nanocrystalline Mg 2 TiO 4 Thin Films
Author(s) -
Ho YiDa,
Su ChiaHui,
Huang ChengLiang
Publication year - 2014
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.12775
Subject(s) - photoluminescence , annealing (glass) , materials science , nanocrystalline material , band gap , thin film , analytical chemistry (journal) , sol gel , nanotechnology , optoelectronics , chemistry , metallurgy , chromatography
In this work, undoped Mg 2 TiO 4 thin films were fabricated on p ‐type Si (111) substrates by the sol–gel method, and the red photoluminescence (PL) of the films is introduced and discussed. According to the experimental results, the red emission appears when the films have been thermally treated at higher temperatures, which have a long range and well‐organized crystalline arrangement. Furthermore, to have better realization of the red emission mechanism of Mg 2 TiO 4 films, the optical band gap of Mg 2 TiO 4 ( E g Mg2TiO4 ) was estimated at ~3.7 eV; furthermore, 325 nm (corresponding energy, h ν = 3.82 eV > E g Mg2TiO4 ) and 633 nm (corresponding energy, h ν = 1.96 eV < E g Mg2TiO4 ) excited light sources were used to clarify the position of the defect levels. In addition, the influence of annealing atmospheres ( O 2 , air, and vacuum) on the red emission of our samples is also discussed. A significant variety of red emissions can be found between these annealing conditions: the red emission can be effectively enhanced by O 2 annealing, but weakened by vacuum annealing. Results reveal that the red emission of Mg 2 TiO 4 thin films may be highly dependent on the completeness of the O–X–O (X = Mg , Ti ) bonds.