Rare earth Sm³⁺ co-doped AZO thin films for opto-electronic application prepared by spray pyrolysis

Samarium and aluminium co-doped ZnO (Sm:AZO) thin films were deposited on glass substrate by nebulizer spray pyrolysis technique with different Sm doping concentrations (0 at%, 0.5 at%, 1 at% and 1.5 at%). X-ray diffraction patterns confirm the polycrystalline nature of prepared films with hexagonal crystal structure. The average crystallite size was found to be reduced with Sm doping due to increased lattice defects. The Raman spectra exhibited characteristic ZnO wurtzite structure confirmed through the presence of E₂-high mode peak at 438 cm⁻¹. The surface topology analysis revealed uniformly distributed wheat shaped particles without any pinholes for 1 at% Sm doped ZnO film. Sm:AZO films displayed high transparency which is around 90% and the energy gap of ~ 3.30 eV. Photoluminescence spectra of the thin films showed an UV emission peak at ~ 386 nm corresponds to near band edge (NBE) emission of bulk ZnO. Room temperature Hall Effect measurement showed that all the prepared films possess n-type conducting nature with low electrical resistivity (ρ) 4.31 × 10⁻⁴ Ω cm for 1 at% Sm doped film. High figure of merit (ф) value of ~ 11.9 × 10⁻³ (Ω/cm)⁻¹ was observed which indicates that the deposited films are highly suitable for opto-electronic device applications.