Physical properties of ultrasonically spray deposited Yttrium-doped SnO2 nanostructured films: supported by DFT study

The physical properties of ultrasonically spray deposited Yttrium (Y) doped tin dioxide (SnO2) are experimentally and theoretically investigated. The different diagnostics techniques such as X-ray diffraction (XRD), UV–Vis, scanning electron microscopy (SEM) and Hall effect measurements were performed to analyze the influence of yttrium doping ratio on the structural, optical and electrical properties of Y-doped SnO2 nanostructured films. Additionally, density functional theory (DFT) is applied to calculate and check the energy gap, lattice parameters and optical properties of SnO2 with different Y doping ratios. Super cell of Y-doped SnO2 was formed using Wien2k, and analyzed to physical properties of un-doped and Y doped stoichiometry with different ratios. Theoretical results are in agreement with the experimental results and the literature reports. Experimental results show that the optical band gap of fabricated sample increases with the increasing the Y doping amount in the tin dioxide film. The same tendency of energy band gap is observed with DFT calculation for Y-doped SnO2 compound. Theoretical results also show that the lattice parameter is nearly the same for pure and Y-doped SnO2 case, attributed to a change in the stoichiometry owing to metal doping. XRD results reveal that the all fabricated films are polycrystalline in the tetragonal Bravais lattice of tin dioxide, and the crystallite size, the crystalline orientation are affected by the Y doping level. The nanosized grains of the produced films are manipulated with increasing the Y dopant confirmed by the SEM. Y doped nanostructured films show the higher optical transmittance about 90% in ultra-violet region. Optical band gap gets widen from 3.689 to 3.810 eV with increasing the dopant amount. From Hall effect results, lower resistivity, higher carrier concentration and high enough mobility have been achieved by Y doping for the sample 5 at% Y:SnO2 based TCO film. The obtained results declared that Yttrium doping has an important effect on the optoelectronic properties, in particular, transparency and conductivity of SnO2 nanostructured film.