MOCVD growth and characterization of TiO2 thin films for hydrogen gas sensor application

TiO2 thin films were deposited on silicon substrates by metalorganic chemical vapor deposition (MOCVD). The deposited films were characterized using scanning electron microscopy (SEM) and Xray diffraction (XRD). We investigated TiO2 thin films growth parameters in relation to the film's physical properties. The growth temperature is the most important growth parameter that influences crystal orientation, grain size and surface morphology of the grown TiO2 thin films. The TiO2 films were utilized as hydrogen gas sensing layer and we characterized their response on the expose to hydrogen gas. We measured hydrogen gas sensing properties and analyzed them by correlating the film's physical properties with the gas sensing properties. Hydrogen gas sensor utilizing TiO2 thin films are able to detect hydrogen gas at concentration of 1000-10 000 ppm with high response. It is found that smaller the grain size and thinner the film thickness give higher sensor response as well as faster response and recovery time.