Physical characterization of sputter-deposited amorphous tungsten oxynitride thin films

Nunez, O.R.; Tarango, A.J. Moreno; Murphy, Neil R.; Phinney, Lucas; Hossain, Khandker S.; Ramana, C. V.

doi:10.1016/j.tsf.2015.08.066

Cited by 9 publications

(13 citation statements)

References 42 publications

(100 reference statements)

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“…The lack of additional energy, either by substrate heating (thermal energy) or substrate bias voltage (electrical energy), is the main reason for the amorphous character of the W-O-N films under variable gas flow rates. This is in agreement with earlier reports, where an amorphous structure is noted for several of W-oxide or W-Ti mixed oxide thin films [2,9]. Scanning electron microscopy (SEM) images of W-O-N films deposited under variable nitrogen gas flow rate are shown in Fig.…”

Section: Resultssupporting

confidence: 92%

“…The n values obtained (Fig. 7a) in this work for W-O-N films without any nitrogen in reactive gas mixture are close to that of bulk WO 3 , indicating that the films are comprised of a W-oxide phase with stoichiometry close to WO 3 [2]. The optical constants of the W-O-N films, deposited at nitrogen gas flow rates at 9 sccm, indicate more or less similar behavior and magnitude.…”

Section: Resultssupporting

confidence: 67%

“…6a) indicate that the k value of the samples is almost zero in the visible and near infrared spectral regions, while for photon energies towards ultraviolet region, 'k' increases sharply. Strong absorption with no weak shoulders or tailing behavior for the W-O-N films without any nitrogen in the reactive gas mixture can be attributed to the typical oxide (insulating) behavior with very high transparency [2,25]. A remarkable change in k(l) profiles can be noted for W-O-N films deposited at higher nitrogen gas flow rates (>9 sccm).…”

Section: Resultsmentioning

confidence: 80%

“…All the films exhibit diffuse patterns, the characteristic of amorphous nature of the W-O-N films. While a detailed discussion of the results and data is reported elsewhere [2], the results are summarized briefly for the benefit of understanding the current work. The lack of additional energy, either by substrate heating (thermal energy) or substrate bias voltage (electrical energy), is the main reason for the amorphous character of the W-O-N films under variable gas flow rates.…”

Section: Resultsmentioning

confidence: 99%

“…It should be noted that the n value is directly related to the material density and molecular polarizability. Therefore, the increasing n-values for W-O-N films with increasing nitrogen flow rate ratio must be a result of changes in the material density as well as changes in molecular polarizability, or a combined effect thereof [2,25].…”

Section: Resultsmentioning

confidence: 99%

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Nitrogen incorporation and composition facilitated tailoring of the optical constants and dispersion energy parameters of tungsten oxynitride films

Nunez

Tarango

Murphy

et al. 2016

Journal of Alloys and Compounds

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a b s t r a c tOptical properties, including the index of refraction, extinction coefficient and band gap of 100 nm thick tungsten oxynitride (W-O-N) films are reported. In addition, the Wemple and DiDomenico (WDD) model was used to calculate the dispersion energies and oscillator energies of the films, establishing a correlation among the films' optical, chemical, and physical properties, as a function of nitrogen content. Nitrogen concentration in the W-O-N films was varied by adjusting the nitrogen gas flow rate from 0 to 20 sccm while keeping total gas flow (nitrogen þ oxygen þ argon) constant at 40 sccm. Both the index of refraction (n) and extinction coefficient (k) of W-O-N films demonstrated a high degree of sensitivity to the nitrogen content during deposition. The optical constants of films fabricated without any nitrogen correspond to transparent W-oxide (WO 3 ) where n 550 ¼ 2.1 and k 550 ¼ 0.0. The magnitude of the spectral response for both n and k tends to increase with increasing nitrogen content. Systematic increases of the films' nitrogen content lead to the formation of W-oxide (E g z 3 eV) / W-O-N oxynitride semiconductor (E g z 2 eV) / N-rich W-O-N semi-metal (E g < 2 eV) / WN 2 type metallic transition was evident in dispersion profiles of n and k for W-O-N films with increasing nitrogen content. The corresponding mechanical characteristics, namely hardness (H) and Young's modulus (E), attain a maximum of 4.46 GPa and 98.5 GPa, respectively, at a nitrogen flow rate of 5 sccm, at which point H and E values decrease to attain 3.57 GPa and 72.91 GPa, respectively. The trend observed in H and E values correlate with the W-O and W-N bonds formation in W-O-N along with the interruption of local epitaxy attributed to increasing nitrogen content within the growth chamber. A correlation among the nitrogen content, optical constants and physical properties, along with the associated dispersion model, is presented to account for the optical properties of sputter-deposited W-O-N films. The results demonstrate that tailoring the properties of W-O-N films for desired applications can be achieved by tuning the nitrogen content and chemical composition.

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Section: Resultssupporting

confidence: 92%

Section: Resultssupporting

confidence: 67%

Section: Resultsmentioning

confidence: 80%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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