HUMIDITY-SENSITIVE CHARACTERISTICS OF SNO2-FE2O3 THIN-FILMS PREPARED BY SPRAY-PYROLYSIS

The humidity sensitivity of mixed iron oxide-tin oxide films has been investigated. The films were deposited by spraying alcohol solution of SnCl4 and Fe(NH4) (SO4)2 or Fe2(C2O4)3 on to quartz substrates heated at 480-degrees-C with subsequent annealing in various ambients - oxyg en or humid air. The films were investigated by Auger electron spectro scopy (AES) and scanning electron microscopy (SEM). The humidity-sensi tivity characteristics are plotted in the range 0%-93% RH. It was esta blished that the humidity sensitivity, the response and the recovery t ime depend on the type of solution used for deposition, the type of th ermal treatment, and the film thickness. It was found that the nature of the iron salt, used for the preparation of the spraying solution, a nd its concentration are of great importance for the humidity-sensitiv e properties of the films. The SnCl4 and Fe2(C2O4), films, treated the rmally in humid air at 900-degrees-C for 1 h, possessed a short respon se time and high sensitivity to moisture.