Optical properties of thin films of mixed Ni–W oxide made by reactive DC magnetron sputtering

Abstract

This is an author produced version of a paper published in Thin Solid Films. This paper has been peer-reviewed but does not include the final publisher proofcorrections or journal pagination. AbstractThin films of Ni x W 1-x oxides with x = 0.05, 0.19, 0.43 and 0.90 were studied. Films with thicknesses in the range 125 -250 nm were deposited on silicon wafers at room temperature by reactive DC magnetron co-sputtering from targets of Ni and W. The films were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), and spectroscopic ellipsometry (SE). XRD spectra and SEM micrographs showed that all films were amorphous and possessed a columnar structure. The ellipsometric angles Ψ and Δ of as-deposited films were measured by a rotating analyzer ellipsometer in the UV-visible-near infrared range (0.63-6.18 eV) and by an infrared Fourier transform rotating compensator ellipsometer in the 500-5200 cm -1 wavenumber range. SE measurements were performed at angles of incidence of from 50° to 70°. Parametric models were used to extract thicknesses of the thin films and overlayers of Ni x W 1-x oxide at different compositions, band gaps and optical constants. Features in the optical spectra of the Ni x W 1-x oxides were compared with previous data on tungsten oxide, nickel oxide and nickel tungstate.

Optical properties of hydrated tungsten trioxide 3WO3·H2O

“…The thicknesses of the films and their dielectric functions have been extracted from experimental data using a parametric model as well as a pbp fit. The obtained dielectric functions are in good agreement with the earlier published IR spectra of 3WO 3 ·H 2 O [3,4,7,12] and the presence of ½WO 3 ·H 2 O compounds in the films is indicated. Moreover, it was proved that films retain a great amount of water, especially the film with a thickness of 2127 nm.…”

Ellipsometrically determined optical properties of nickel-containing tungsten oxide thin films: Nanostructure inferred from effective medium theory

“…Film thicknesses lay between 124 and 304 nm, with thickness non-uniformities around 4%. 16 We obtained results on Figs. 3 and 4. It should be noted that some correlations appear between the parameters of the Gaussian oscillators, which implies that the solutions are not unique and there exist multiple sets of Gaussians which provide the same dielectric functions.…”

“…18 A detailed description of the parametric model used to represent the Ni x W 1Àx oxide films is given elsewhere. 16 …”

“…Furthermore, NiWO 4 is known as an electrochromic material. 13 We have therefore embarked on a comprehensive investigation of the full Ni x W 1Àx oxide system, with 0 x 1, and previously reported on the compatibility of these oxides with different electrolytes, 14 optical properties as determined by spectroscopic ellipsometry, 15,16 as well as nanostructures and compositions recorded by Raman spectroscopy, x-ray photoelectron spectroscopy, x-ray diffractometry, and Rutherford backscattering spectrometry. 17 Furthermore, we have studied the electrochromism for films with 0 x 0.6.…”

Electrochromic Metal Oxides: Recent Progress and Prospect

“…[10] Researches on metal doping have been performed on Nb, [20] Mo, [17] Ni, [46,47] Ti, [48] Ru, [49] V, [50] Ce, [51] and Sn, [52] and the results have shown that WO 3 with metal doping can have superior properties in one way or another. [10] Researches on metal doping have been performed on Nb, [20] Mo, [17] Ni, [46,47] Ti, [48] Ru, [49] V, [50] Ce, [51] and Sn, [52] and the results have shown that WO 3 with metal doping can have superior properties in one way or another.…”