Unveiling growth and characterization of alkali metals-doped SnS2 thin films for resistive humidity sensing

Tin disulfide (SnS₂) thin films, prized for their diverse structural and electrical properties, are increasingly explored for practical applications. This study investigates the controlled doping of SnS₂ with selected alkali metals (Li, Na, and K) via a spray-coating method to enhance its functionality, particularly in resistive humidity sensing. The deposition process, meticulously designed for uniformity and reproducibility, incorporates precise concentrations of dopants to modulate film characteristics. X-ray diffraction analysis reveals alterations in lattice parameters and crystallite size (increase from 10 nm to 18 nm) due to doping. X-ray photoelectron spectroscopy elucidates shifts in binding energies and stoichiometry changes induced by dopants. Electrical investigations demonstrate semiconductor behavior, with doped films exhibiting reduced resistance and increased capacitance under humidity, which is critical for humidity sensing. Particularly, Li-doped films display a sensitivity of 18.78 pF/ % RH and a response time of 85 seconds, suggesting promising applications in humidity sensing technology. This comprehensive study provides insights into the intricate interplay between dopants and SnS₂ properties, paving the way for tailored material design and sensor development.