Effect of thermal treatment on thin films of NiO:WO3 for optoelectronic applications

초록

Nickel oxide (NiO), a semiconducting metal oxide, with its exceptional optical, electrical, and magnetic properties make it highly sought after for use in optical, optoelectronic, and electrochromic devices. Recent advancements in NiO-optical devices relies on the optical parameters like intrinsic optical nonlinearities. The current study involves the deposition of NiO:WO3 thin films utilizing radio frequency (RF) sputtering at various substrate temperature (Ts) of 100, 200, and 300 degrees C. An investigation was carried out to analyse the significance of Ts on the structural, optical, morphological, & vibrational characteristics. The X-ray diffraction investigation revealed the amorphous nature of the films. Scanning electron microscopy confirms the compact pinhole free surface of the films. The results of energy dispersive X-ray spectroscopy (EDS) spectra verified the existence of nickel (Ni), oxygen (O), and tungsten (W) components in the films. XPS analysis confirms the presence of both Ni2+ and Ni3+ states. The optical transmittance increased, and the band gap decreased with increase in Ts. The impact of Ts on various optical parameters such as refractive index, extinction co-efficient, dielectric constants, optical non-linear susceptibility, and dispersion energy parameters obtained by the Wemple-DiDomenico theory has been calculated and extensively investigated. The results indicate that NiO:WO3 films can be used to fabricate electrochromic and optoelectronic devices.

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