Ethanol response of semiconductor gas sensors based on SnO2 layer prepared from acidic solution

We examined the response behavior of SnO2 based semiconductor gas sensors to ethanol. In this study, the sensing layer was fabricated from mixed solutions of tin acidic standard solution with zinc or titanium acidic standard solution. The sensitivity of SnO2 sensors prepared from acidic standard solutions to ethanol was higher than that of metal-doped SnO2 sensors prepared from SnO2 powders. The sensitivity of Zn-doped SnO2 sensors was depressed in the humidified environment, while the sensitivity of Ti-doped SnO2 sensors was not affected by humidity even if the relative humidity was high. SnO2 films prepared from SnO2 powders composed of particles with 100 nm mean particle diameter. By using tin standard solution as a material of film, semiconductor films formed of fine particles having 10 nm mean particle diameter were obtained. This film formation method using acidic standard solutions can control the thickness of film easy, and the thin SnO2 film with around 100 nm thickness could be obtained.