Impact of Ni doping on the structural, morphological, electrical and optical properties of SnO2 thin films by spray pyrolysis technique

This work deals with the impact of Ni doping on the structural, morphological, electrical and optical characteristics of SnO2 thin films, deposited on soda-lime glass microslides (75 mm × 25 mm × 1.2 mm) at 400 °C by facile spray pyrolysis technique. The structural analysis (XRD) confirms that the prepared Ni:SnO2 thin films belong to the tetragonal rutile structure. The preferred growth orientation along the (211) and (301) planes shifted to the (200) plane due to the Ni dopant concentration. Scanning electron microscopic analysis reveals that the grain size is effectively modified by various nickel concentration in the films. XPS measurement indicates the presence of Sn4+ and Ni2+ in 3.0 at.% Ni:SnO2 thin film. The electrical studies reveal that all the films show n-type conductivity. The lowest resistivity (2.4 × 10–3 Ω cm), high carrier concentration (1.267 × 1020 cm−3) and high mobility (120 cm2/V s) are obtained for undoped SnO2 thin films. A slight variation in the resistivity and carrier concentration is observed for Ni-doped SnO2 films. The optical transmittance of 2.0 at.% Ni:SnO2 film shows maximum transmittance than undoped SnO2 film. The photoluminescence spectrum of undoped SnO2 and Ni:SnO2 thin films, excited at the wavelength of 325 nm, consists of the strong near band emission at 398 nm. The obtained result shows that 2.0 at.% Ni:SnO2 film has high optical and electrical conductivity; this could be useful in optoelectronic and gas sensing applications.