Characterization of Zn doped SnO₂ thin films prepared by the SILAR technique for optoelectronic applications

In the present study, pure and zinc (Zn) doped tin oxide (SnO₂) thin films were grown by successive ionic layer adsorption and reaction method on the soda lime glass slides at 293 K. The prepared samples were examined to observe the impact of Zn doping on structural, morphological, electrical, and optical properties of SnO₂ crystal lattice. The x-ray diffractometer (XRD), ultraviolet–visible spectrometer, energy dispersive x-ray analysis (EDAX), scanning electron microscope (SEM), Raman, x-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectra measurements were conducted. And, two probe detection method was applied to find the shift in resistance values corresponding to varying temperatures. The XRD results depicted that the prepared thin films have the tetragonal rutile structure. The surface morphologies were observed to be affected by the changing concentrations of Zn doping. The EDAX evaluation exposed the existence of Zn ions in the prepared samples in addition to Sn and O. Resistivity vs temperature (r–t) measurements exhibited that all the samples possess the common 'r–t' characteristics of semiconductors. The XPS results uncovered the fact that the binding energy of SnO₂ nanostructures was decreased by 0.9 eV due to the existence of Zn ions. It was also found out that the band gaps, calculated by using the absorption measurements, can be tuned from 2.02 eV to 2.50 eV by the different rates of Zn dopants in the SnO₂ nanostructures. The Raman spectras of pure SnO₂ and Zn doped SnO₂ (Zn:SnO₂) samples gave three peaks that were in the range of 490 cm⁻¹, 580 cm⁻¹ and 620 cm⁻¹ for each peak separately. The PL spectra displayed that the emission intensity decreased with the introduction of impurities into the SnO₂ lattice. (paper)