Characterization of indirect and direct interband transitions of anatase TiO2 by thermoreflectance spectroscopy

Ho, Ching-Hwa; Tsai, Ming-Cheng; Wong, Ming-Show
August 2008
Applied Physics Letters;8/25/2008, Vol. 93 Issue 8, p081904
Academic Journal
We characterize three as-deposited anatase TiO2 (a-TiO2) films with different deposition flux angles of 0°, 53°, and 86° tilted to Si <001> using thermoreflectance (TR) measurement in the temperature range between 30 and 300 K. The TR spectra at low temperature clearly show considerable difference in interband transitions of the tetragonal a-TiO2 with the largely top plane of {001} or the largely side planes of {100} and {010}. The indirect and direct interband transitions of the a-TiO2 are evaluated. The temperature dependences of the interband transition energies of the a-TiO2 are analyzed. The optical-axial anisotropy of the a-TiO2 films is discussed.


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