Characterization and testing of Pt/TiO2/SiC thin film layered structure for gas sensing

This paper presents the results of our investigations on the gas sensing performance of Pt/TiO2/SiC based field effect devices. The current-voltage characteristics of these Pt/TiO2/SiC sensors at 530 °C showed a clear shift to lower voltages upon exposure to increasing hydrogen gas concentration. This indicates a reduction in the metal-oxide interface barrier height, arising from the flattening of the energy bands at the interface and can be attributed to the lowering of the Pt work function due to absorption of hydrogen. The effective change in barrier height Δφb for 1% hydrogen in air was found to be 125 meV. The thermal stability of the interfaces in the Pt/TiO2/SiC devices was studied by Rutherford backscattering spectrometry (RBS). The RBS spectra of the sample in as deposited and annealed conditions were compared and analyzed. The Pt/TiO2 and TiO2/SiC layers showed a sharp interface with minimal inter-diffusion. The film composition found to be stable even after repeated testing by exposing to analyte gases. This was further confirmed by X-ray photoelectron spectroscopy analysis of the samples.