Ethanol gas detector using zinc-oxide-based coatings

摘要

Undoped and doped ZnO-based films were prepared on alumina substrates by spray pyrolysis for gas sensor applications. Samples were doped with Al, Cu, In and Sn. The energy dispersive of x-rays measurements have shown that the atomic percent ratios of the doping elements in the films are proportional to doping concentration in the pyrolytic solution X-ray diffraction results show that grain size and preferential crystal growth direction defend on the type and amount of dopants. The ethanol vapor detection defends on the coating temperature during vapor-solid interaction. We have found that the optimized detection conditions for ZnO-based coatings are found around 400 °C. All samples (doped and undoped) increase their electrical conductance as vapor concentration increases in the air-vapor mixture, surrounding the sample. Samples doped with Sn, Al and In showed more sensitivity for ethanol detection respect to undoped and Cu-doped samples. ZnO:Sn samples with 0.15 atomic ratio of tin-zinc exhibits the best sensitivity to ethanol vapor, at a sensing temperature of 400 °C.