Nd³⁺ Doping effect on the optical and electrical properties of SnO₂ thin films prepared by nebulizer spray pyrolysis for opto-electronic application

Neodymium doped tin oxide (Nd: SnO₂) thin films were deposited on heated glass substrates with different Nd concentrations (0, 2, 4 and 6 %) by nebulizer spray pyrolysis method. Effects of Nd doping on structural, optical and electrical properties of the prepared films were investigated. X-ray diffraction study confirmed that all the deposited Nd: SnO₂ films are in polycrystalline tetragonal structure with (211) preferential orientation. FESEM images showed that the prepared SnO₂ particles are in nano-size in spherical shape, completely covering the substrate. AFM topology showed smooth deposition of the films with minimum surface roughness. The films showed maximum optical transmittance 90 % in the visible region with a band gap value 3.67 eV, also showed low refractive index and extinction coefficients. Room temperature photoluminescence (PL) spectrum exhibited a strong UV emission peak at 356 nm for all the films. All the Nd: SnO₂ films displayed n-type conductivity with low electrical resistivity 5.88 × 10⁻⁴ (Ω cm) for 4 % Nd doping. As the films showed good figure of merit (ϕ) values, these Nd doped SnO₂ thin films can perform better role in optoelectronic device.