Structural and thermoelectric properties of SnO2:Bi thin films

In this work, the preparation and study of structural and thermoelectric properties of thin films of SnO
2
and SnO
2
:Bi are reported. Undoped and doped films were deposited by spray pyrolysis technique at 400 °C. The XRD characterization shows deterioration in the crystalline quality of the samples when the amount of dopant increases. The crystallite size in the samples decreases when the amount of dopant (Bi) increases. Sn
⁴⁺
ion was replaced by Bi
³⁺
ion in the lattice of the material. This reduces the concentration of charge carriers but maintains n-type conductivity. The reduction in the concentration of charge carriers and the defects present in the lattice increase the electric resistivity of the material from 2.411x10
^-2
Ω∙cm to 1.886x10
²
Ω∙cm. The Seebeck coefficient increases up to -200 μV/K. However, the sample undoped presented the highest power factor, with a value of 0.51 μW/cm∙K
²
. This is because the element Bi creates an insulating effect on the samples both thermally and electrically.