Investigation of gas-sensitive properties of cobalt oxide films

Abstract

Abstract This paper presents a study of the gas-sensitive properties of cobalt oxide films formed by rapid thermal annealing on a sitall substrate. Cobalt films were formed on a pre-cleaned sitall substrate by vacuum thermal evaporation. The thickness of the deposited films was 470 nm. Rapid thermal annealing (RTA) was used to form cobalt oxide films. RTA of cobalt films was carried out at temperatures of 500°C, 600°C and 700°C. The resistivity of the films after RTA at 500°C, 600°C and 700°C was 3.6 × 10–2 Ohm·cm, 1.2 × 103 Ohm·cm and 5.8 × 103 Ohm·cm, respectively. The surface morphology of the obtained films was investigated by the AFM method. The gas sensitivity of cobalt oxide films was studied for gases like CO, NO2, CH4, C3H6O (vapors of acetone), C3H8O (vapors of isopropyl) and NH3·H2O (vapors of ammonium hydroxide 25%). The gas sensitivity was measured at 300°C. The results of gas sensitivity measurements showed significantly lower sensitivity to gases such as CO, NO2 and CH4. It was found that cobalt oxide films have good sensitivity to gases such as C3H6O, NH3·H2O and C3H8O. Sensitive elements based on cobalt oxide films are interesting as gas sensor elements for the detection of C3H6O, NH3·H2O and C3H8O.