New devices Si-rich and C-rich a-Si1−xCx thin films gas sensors based

In this paper, we present an experimental study on elaboration of Si-rich and C-rich thin films of hydrogenated amorphous silicon carbide (a-Si1−xCx:H) using a DC magnetron co-sputtering of Si single crystal target on which are deposited different polycrystalline 6H-SiC sprigs varying from 32 to 86, with dimension of 10 × 5 mm2. A comparative study of structural and optical properties has been performed and its applications in environmental field. The a-Si1−xCx:H films were investigated by scanning electron microscopy (SEM), UV-visible-NIR spectrophotometry, infrared absorption spectroscopy, secondary ion mass spectrometry (SIMS), and photoluminescence. The measured optical gap of a-Si1−xCx:H thin films depend on the carbon concentration with x varying from 0.18 to 0.30. This can be probably explained by the changes of Sp3 (silicon or film with low carbon content) to sp2 (high carbon content) configuration. Finally, different devices structures based the thin films have been investigated as gas sensors as Pd/a-Si0.72C0.28:H with a good sensitivity of CO2 and H2 gases at low bias voltage ranging from 0.05 to 0.26 volt, respectively and a low response time of 29 s and 25 s was obtained at 165 ppm of the used gases, with a recovery time of 32 s and 23 s for CO2 and H2 gases, respectively.