Revealing the significance of Ga-doped WO3 thin film gas sensor prepared by spray pyrolysis technique for detecting acetaldehyde

Aldehydes continue to be a source of regulatory and scientific concern in the air since they are widely present in the environment and may be harmful to human health. Acetaldehyde, a common environmental pollutant and a major metabolite of alcohol, poses several risks to human health. It is the primary cause of the majority of respiratory and liver-related deaths worldwide, with lower- and middle-income nations suffering the lion's share of this burden. The increased risk of cancer and mortality rate of the disease can be decreased by keeping an eye on the air quality and identifying the underlying causes of the chemicals. Thus, Pure WO3 and gallium-doped thin films were deposited by a direct one-step process to detect acetaldehyde gas at room temperature. The spray- deposited thin films were characterized for optical, structural, morphological and gas-sensing studies. The hexagonal phase of WO3 and gallium-doped WO3 films were highly crystalline. The Ga-doped samples have high surface roughness and grain boundaries than the pristine WO3, contribution to the increase in the adsorption of gas molecules. High carrier density can modify the band structure, resulting in band gap narrowing. Additionally, as donor concentration increases with heavy doping, the Fermi level shifts, leading to a redshift in the material's optical properties. FE-SEM analysis reveals that smooth filamentous structured porous films of pure and rough texture filamentous porous films doped with Ga exhibit larger pores, facilitating increased adsorption of gas molecules. A high sensing response of 98.09 S was obtained at room temperature for acetaldehyde gas by 0.075 % gallium-doped WO3 thin film.