Effects of cation compositions on the electronic properties and optical dispersion of indium zinc tin oxide thin films by electron spectroscopy

• REELS analysis can provide optical dispersion and electronic properties of oxide materials.
• The band gap varied with In/Zn/Sn compositions and increased after annealing.
• The optical properties were examined using REELS in conjunction with the Tougaard–Yubero model.
• The dispersion parameters were determined by a single-oscillator Wemple–DiDomenico model.
• The Zn and Sn contents play a crucial role in determining the single-oscillator constant and dispersion energy of IZTO thin films.

The electronic properties and optical dispersion of indium zinc tin oxide (IZTO) films with different cation compositions were investigated by reflection electron energy loss spectroscopy (REELS). The REELS spectra of IZTO films revealed that the band gap varied with different Sn/Zn ratios and In content. The optical properties were examined with REELS data using Tougaard–Yubero model and the results were compared with the envelope of the transmission spectra obtained using a UV-spectrometer. The dispersion behavior of the refractive index from REELS results was studied in terms of the single-oscillator Wemple–DiDomenico model. The results showed that the different compositions of In/Zn/Sn caused a change in the dispersion parameters of IZTO thin films in contrast to the static values of refractive indices and dielectric constant which remained the same. Our work demonstrated that REELS is an efficient tool to study the optical properties of a material by obtaining the optical parameters.

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