Effects of deposition parameters on optical and electrical properties of Colloidal SnO2 film

This study investigates the influence of deposition parameters specifically precursor concentration and annealing temperature on the optical and electrical properties of sol–gel spin-coated SnO ₂ thin films. Films were fabricated from 5, 10, and 15 wt.% SnO ₂ aqueous colloidal dispersions deposited on Si(001) and glass substrates and annealed between room temperature and 150°C. Rutherford backscattering spectrometry (RBS) confirmed stoichiometric SnO ₂ composition with film thicknesses ranging from 49 nm to 90 nm. Electrical characterization using the van der Pauw and Hall effect methods revealed that resistivity decreased from 203.6 µΩ cm to 179.8 µΩ cm as both precursor concentration and annealing temperature increased, primarily due to enhanced carrier concentration and reduced grain boundary scattering. Carrier concentration increased from (7.0 ± 0.4) × 10²⁰ cm⁻³ to (8.2 ± 0.3) × 10²⁰ cm⁻³, while mobility remained stable around 40–44 cm² V⁻¹ s⁻¹. Optical transmittance exceeded 80% across the visible spectrum, and the optical bandgap decreased slightly from 3.78 eV to 3.69 eV with increasing precursor concentration. The findings demonstrate that controlled tuning of precursor concentration and annealing temperature can enhance the conductivity and optical transparency of SnO ₂ films, making them promising electron transport layers for optoelectronic applications such as perovskite solar cells.