Photoluminescence and Optical Absorption of Pure NanocrystallineTiO2 Anatase and Rutile at Room Temperature

Authors L. Kernazhitsky1, V. Shymanovska1, T. Gavrilko1, V. Naumov2, L. Fedorenko2 , V. Kshnyakin3

1 Institute of Physics, NAS of Ukraine, 46, Pr. Nauky, 03650 Kyiv, Ukraine

2 Institute of Semiconductor V.E. Lashkareva, NAS of Ukraine, 41, Pr. Nauki, 03028 Kyiv, Ukraine

3 Sumy State University, 2, Rimsky-Korsakov Str., 40007 Sumy, Ukraine

Issue Volume 5, Year 2013, Number 3
Dates Received 12 April 2013; published online 17 October 2013
Citation L. Kernazhitsky, V. Shymanovska, T. Gavrilko, et al., J. Nano- Electron. Phys. 5 No 3, 03047 (2013)
PACS Number(s) 61.46. + w, 61.72.Ji, 71.35. – y, 33.50.Dq
Keywords Titanium dioxide (4) , Anatase, Rutile, Photoluminescence (17) , Optical absorption (3) .
Annotation The optical absorption and photoluminescence of nanocrystalline TiO2 samples of anatase and rutile were investigated at room temperature. Nanocrystalline TiO2 samples were synthesized in the form of pure anatase or rutile and studied by X-ray diffraction, X-ray fluorescence, Raman spectroscopy, optical absorption and photoluminescence (PL). PL was studied at room temperature when excited by intense UV (3.68 eV) by a nitrogen laser. For the first time for nanocrystalline TiO2 a features in the high-resolution PL spectra, including the exciton band and interband transitions were registered. It is concluded that the processes of absorption and emission of light near the edge of the forbidden zone occur with the participation of the same electronic transitions. PL bands, including the peaks at 2.71-2.81 eV in the anatase and rutile arise due to exciton recombination in the TiO2 lattice oxygen vacancies. The exciton peak at 2.91 eV is attributed to the recombination of self-trapped excitons in anatase or to the free exciton in rutile, respectively. PL bands within 3.0-3.3 eV attributed to indirect and direct allowed transitions due to electron-hole recombination. PL bands at 3.03 eV and 3.26 eV, attributed to the emission of free excitons near the fundamental absorption edge of rutile and anatase, respectively. The influence of TiO2 crystal structure and calcination temperature of the samples on the PL spectra and optical absorbtion is discussed.

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