Wide-range ethanol sensor based on a spray-deposited nanostructured ZnO and Sn–doped ZnO films

This study compares the performance of a highly sensitive ethanol sensor incorporating a zinc oxide (ZnO) nanostructured film with that of (1–3) % tin-doped zinc oxide (Sn–ZnO) nanostructured films across a wide range of ethanol concentrations from 0.5 to 400 ppm. X-ray diffraction analysis confirms the polycrystalline structure of Sn–ZnO films, with a significant (002) plane orientation. Notably, Sn doping reduces the optical bandgap from 3.28eV (ZnO) to 2.41eV (3% Sn–ZnO). Ethanol vapor sensing experiments reveal that the 2% Sn–ZnO film operates at a lower temperature of 220 °C compared to the ZnO film (290 °C). Particularly, the 2% Sn–ZnO film exhibits rapid and strong responses to low ethanol concentrations (0.5–100 ppm) at this temperature. Response values of 2.20 ± 0.01 and 17.60 ± 0.08 with response times of 11 ± 1 and 15 ± 1s are achieved at ethanol concentrations of 0.5 and 400 ppm, respectively. Conversely, the ZnO film performs better at higher ethanol concentrations (150–400 ppm). These findings advance gas sensing mechanisms in ZnO and Sn–ZnO films, with implications for future advancements in gas sensor technology.