Infrared absorption peak due to Ta=O bonds in Ta2O5 thin films

Abstract

Ta 2 O 5 films deposited on Si substrates were investigated using transmission Fourier-transform infrared spectroscopy. We found a new absorption peak at 2340 cm−1 that can be characterized as a stretching vibration mode due to Ta=O bonds in the films. This peak appeared following annealing in O2 ambient, but not in N2 ambient. It was located at 2335 cm−1 in amorphous Ta2O5 films and shifted to 2340 cm−1 after crystallization by annealing at over 700 °C. The bonds associated with the peak were homogeneously distributed in the film. We demonstrated that Ta2O5 films can include strong double bonds between Ta and O (Ta=O) in the structure, independent of whether they are crystalline or amorphous.

Crystallization improvement of Ta2O5 thin films by the addition of water vapor

“…It can be clearly seen that the band at around 600 cm À1 shifts from 640 to 510 cm À1 and the intensity of the peak at 1000-790 cm À1 weakens with the introduction of water vapor. Previously, it was reported [11] that the phonon bands of Ta 2 O 5 are mainly in the range of 1000-200 cm À1 , and Ono and Koyanagi [12] studied carefully the FTIR absorption of crystalline and amorphous Ta 2 O 5 thin films, as shown in Table 1. Among these FTIR peaks, it is noted that the absorption peak at about 640 cm À1 that corresponds to the vibration mode of O3Ta in amorphous Ta 2 O 5 thin films shifts to 510 cm À1 as the film crystallinity improves.…”

Ta 2 O 5 polymorphs: Structural motifs and dielectric constant from first principles

“…Unfortunately, no measurement of IR spectra below 400 cm −1 is available. 31 However Raman spectra 27,28 reveal several features in the far-IR that could not be interpreted in terms of vibrations "internal" to the coordination polyhedra but ascribed 28 to the interaction of the latter with hypothesized "external" clusters. Our results contrast with this speculation and reveal the origin of these modes.…”

Heat treatment induced structural and optical properties of rf magnetron sputtered tantalum oxide films

“…The appearance of broad band at 700 -1000 cm -1 related to the stretching mode of Ta-O-Ta. The prominent band occurred at 610 cm -1 corresponds to the stretching mode of O ≡ 3Ta in amorphous phase of tantalum oxide films [7]. Similar predominant band at about 600 cm -1 was also observed in spin coated films [8].…”