Microstructural, optical and electrical investigations of Sb-SnO2 thin films deposited by spray pyrolysis

• We controlled structural, morphological, electrical, optical and physical (such as band gap energy) properties by altering the Sb doping concentration.
• Variation in bandgap with Sb concentration is in agreement with the Burstein–Moss hypothesis and this hypothesis was further confirmed by plotting Eg vs n2/3.
• The resistivity and mobility are in the range of 1.512–6.624 × 10−3 Ω cm and 9.75–22.96 cm2 V−1 s−1. The e-density lies between 4.11 × 1019 and 4.24 × 1020 cm−3.
• We observed that Sb substitution in SnO2 lattice decreases the crystallite size and the possible reason for this is the creation of Sb monolayer on the surface of SnO2 crystallite.

The structural, optical and electrical properties of spray deposited antimony (Sb) doped tin oxide (SnO2) thin films, prepared from SnCl4 precursor, have been studied as a function of antimony doping concentration. The doping concentration was varied from 0 to 1.5 wt.% of Sb. The analysis of X-ray diffraction patterns revealed that the as deposited doped and undoped tin oxide thin films are pure crystalline tetragonal rutile phase of tin oxide which belongs to the space group P42/mnm (number 136). The surface morphological examination with field emission scanning electron microscopy (FESEM) revealed the fact that the grains are closely packed and pores/voids between the grains are very few. The resistivity (ρ) and mobility (μ) are in the range of 1.512 × 10−3–6.624 × 10−3 Ω cm and 9.75–22.96 cm2 V−1 s−1. The electron density lies between 4.11 × 1019 and 4.24 × 1020 cm−3. A thorough electrical investigation reveals that the film's resistivity depends on carrier concentration. It is found that ionized impurity scattering is the dominant mechanism, which limits the mobility of the carriers. The transmittance spectra for as-deposited films were recorded in the wavelength range of 200–1000 nm. The transmittance of the films was observed to increase from 57% to 68% (at 800 nm) on initial addition of Sb (up to [Sb]/[Sn] = 0.5 wt.%) and then it is decreased for higher level of antimony doping ([Sb]/[Sn] >0.5 wt.%).

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