Low-temperature fabrication method of carbon nanotubes-based gas sensor

Low temperature processes are the better ways to integrate carbon nanotubes (CNTs) with CMOS chips into array-type gas sensors. Almost the metal used in CMOS is Al-Si-Cu alloy, which make the sustainable temperature of CMOS structures be in the range of 400- 500degC. We offer a new fabrication method of CNTs-based gas sensors at low temperature. The oxidized silicon substrate was modified with 3-aminopropyltriethoxysilane (APTS) to form aminoterminated (-NH₂) self-assembled monolayer (SAM) on the surface. The chemical adhesion of CNTs to surface treated is due to the presence of positive charges or amine groups on the surface. After CNTs adhered to SiO₂ surface, we deposited interdigitated electrode (IDE) on the SiO₂ surface. We experimentally found that the resistances of CNT electronic devices at room temperature typically ranged from several hundreds Omega to several of kOmega, depending on the density of the MWCNTs across the IDE fingers. An array-type CNTs-based gas sensor was made up of many CNTs-based gas sensors. The initial resistance values of these sensors were not the same; therefore we tuned the resistance value of gas sensor equally by trimming.