Realization of highly conducting and transparent SnO2 thin films by optimizing F/Sn molar ratio for electrochemical applications

Abstract

In the present work, fluorine-doped and undoped tin oxide thin films were deposited on microscopic glass substrate by nebulized spray pyrolysis technique at a constant substrate temperature of 350 °C. The influence of fluorine doping on the physical properties of tin oxide has been investigated by depositing the films by varying the F/Sn precursor molar ratio. The structural, morphological, chemical, optical and electrical properties of the films were characterized by X-ray diffractometer, transmission electron microscope, selected area electron diffraction, field emission scanning electron microscope, X-ray photoelectron spectroscopy, ultraviolet visible near infrared spectroscopy, and Hall effect measurements. The results suggest that deposited films are well adhered and uniformly deposited on the substrate. The structural analysis exhibit that the films are highly polycrystalline, crystallized in tetragonal structure with preferred orientations perpendicular to (200), (211) and (110) planes, and without any secondary phases. Optical transmittance greater than 75% in the visible region is obtained with an optical bandgap energy lying in the range 3.98 – 4.07 eV. Minimum resistivity, for optimized fluorine doped on tin oxide thin films, was in the range of 9.002×10−4 Ω-cm at room temperature. Hall Effect measurements show that the fluorine-doped films are degenerate semiconductors with n-type electrical conductivity. The analysis results show that device quality, highly transparent and stable fluorine doped tin oxide thin films which are having least resistivity values for the minimum doping concentration of 6.1% of fluorine can be prepared by nebulizer spray pyrolysis technique.