Structural and Optical Properties of Copper-Doped Tin Oxide Films through Spray Techniques

Spray pyrolysis was used to create copper-doped tin oxide (Cu–SnO₂) thin films, which were then analysed for their morphological, structural, optical, and electrical characteristics. With crystallite diameters ranging from 8 to 31 nm, X-ray diffraction revealed lattice strain and verified a tetragonal rutile phase devoid of secondary phases. The substitution of Cu into the SnO₂ lattice was confirmed by Fourier transform infra-red spectra. The optical studies revealed in the absorption edge with a bandgap 3.88eV (1 at% Cu) and a high transmittance (85%).Due to the equilibrium between carrier production and scattering, electrical characterisation showed a minimum resistivity of approximately 6.34Ω•cm at 1 at% Cu doping. At 1% doping, scanning electron microscopeimages showed homogeneous grains; at greater concentrations, agglomeration and surface roughness were observed. These results show that 1 at% Cu doping maximises conductivity and transparency, making Cu–SnO₂ thin films attractive options for solar cells, transparent electrodes, and optoelectronic devices.