Porous single-wall carbon nanotube films formed by in Situ arc-discharge deposition for gas sensors application

A gas sensor structure for high performance is developed based on a porous film structure of single-wall carbon nanotubes (SWNTs). The SWNTs are directly deposited on the substrate in situ in the arc-discharge chamber, and the steric hindrance during the deposition permits high porosity in the carbon nanotube thin film. The SWNTs are characterized and their capacities of sensing NO and NH3 gases are investigated down to 2 ppm-level concentration at room and elevated temperatures. The effect of sensor porosity is examined and compared with that of a nonporous sensor structure. The response and recovery behaviors are examined with temperature variations.