Thickness dependence of dispersion parameters of the MoOx thin films prepared using the vacuum evaporation technique
Küçük Resim Yok
Tarih
2015
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
ELSEVIER SCIENCE SA
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
The optical behaviors of molybdenum oxide thin films are highly important due to their widespread applications. In the present paper, the effect of thickness on the structure, morphology and optical properties of molybdenum oxide (MoOx) thin films prepared on Corning glass substrates using thermal evaporation technique was studied. The structure and morphology of films were characterized using Xray diffraction (XRD) and scanning electron microscopy (SEM), respectively, while their optical properties were investigated by UV-VIS-NIR spectrophotometry in the spectral range from 300 to 2500 nm. It was observed that whole films have amorphous structure and also they showed rather high transmittance values reached nearly up to 90%. Absorption analysis showed two types of electronic transitions; both direct and indirect interband transition energy values of films decrease from 4.47 to 3.45 eV and from 3.00 to 2.75 eV, respectively, with increasing the film thickness, while the width of the localized states tail increases with thickness. This decrease in the band gap value can be attributed to the rising oxygenion vacancy densities with the thickness. The refractive indices of films were calculated from Sellmeier coefficients determined by nonlinear curve fitting method based on the measured transmittance spectral data. The dispersion of the refractive index was discussed in terms of the Wemple-DiDomenico singleos-cillator model. The dispersion parameters such as average oscillator energy, E-o, the dispersion energy, E-d, and static refractive index n(o) were evaluated and they found to vary significantly with the film thickness. (C) 2015 Elsevier B.V. All rights reserved.
Açıklama
Anahtar Kelimeler
Optical constants, Dispersion analysis, Molybdenum oxide thin films
Kaynak
JOURNAL OF ALLOYS AND COMPOUNDS
WoS Q Değeri
Q1
Scopus Q Değeri
Q1
Cilt
647
