Study of a Nanostructured Co-Doped SnO₂ Sensor for Hydrogen Peroxide Vapor Detection Using Impedance Spectroscopy

A hydrogen peroxide vapor (HPV) sensor based on SnO₂ doped with 1.3 at. % Co thin film has been fabricated using the high-frequency magnetron sputtering method. The thickness of the SnO₂ ⟨Co⟩ thin film was measured and the surface morphology was examined using the thickness measurement profilometer and scanning electron microscopy, respectively. The crystalline properties of the sensing material were revealed by transmission electron microscopy. The response, current-voltage, and impedance characteristics of the sensor were measured in the air and in the presence of various concentrations of HPV at 25-200 °C. An equivalent electrical circuit for the manufactured sensor structure was proposed, and the parameters of its constituent elements were determined. Furthermore, fitting frequency dependences of impedance were calculated. It was shown that charge transfer in the SnO₂ ⟨Co⟩ thin film was regulated by the processes mainly occurring at the grain boundaries of the gas-sensing film.