Estudio de puertas catalíticas en sensores de gas en tecnología de SiC

In this work the chemical and structural characterisation of metallic layers of Pt and TaSi x , employed as catalytic gates in high temperature gas sensors based on MOS devices on SiC substrates, is presented. For the study layers of different thickness have been deposited on Si substrates. The results show that the roughness of the layers increases with the reduction of the thickness of Pt and with annealing, which should give rise to an increase in the sensitivity and response speed of the devices. Another consequence of the annealing is the chemical transformation of the gate's materials that, for thin films of Pt with TaSi x , produces the complete transformation of Pt into Pt 2 Ta, which might affect the catalytic properties of the gate. The first electrical results show that, even with thick and compact Pt layers, the SiC-based MOS tunnel diodes are sensitive to CO and NO 2 gases, although the response time is relatively long. its response speed is too slow.