Structural, Optical and Dielectric Properties of Nd Doped NiO Thin Films Deposited with a Spray Pyrolysis Method

Abstract

The effect of Nd doping (1, 3 and 5 wt%) on the structural, morphological, electrical and optical properties of NiO thin films deposited on glass substrates using nebulizer spray pyrolysis method are investigated. The X-ray diffraction study reveals cubic structure with an improvement in crystallinity upon the incorporation of Nd into NiO lattice. The films are > 50% transparent in the high wavelength region. The absorption spectra witnesses a sharp fall in the wavelength range, 300 nm < λ < 600 nm reflecting the semiconducting nature of these films. The optical direct (indirect) band gap values obtained using Tauc’s relation decrease from 3.67 eV (3.00 eV) for pure NiO to 3.38 eV (2.44 eV) for 3 wt% Nd:NiO. The linear refractive index (n) values estimated using different models are compared. Using the average linear refractive index along with optical direct band gap, the high-frequency and static dielectric constants; the linear and non-linear optical susceptibilities and non-linear refractive index are calculated. It is observed that all these quantities enhance with Nd doping whereas the static dielectric constant decreases with an increase in Nd content. The high frequency dielectric constant and static dielectric constant values are observed to vary between 5.08–5.45 and 51–32, respectively. The values of linear and non-linear optical susceptibilities and non-linear refractive index are found vary between 0.325–0.354, 1.90 × 10–12–2.67 × 10–12 esu and 3.17 × 10–11–4.31 × 10–11 esu, respectively.