Growth of single wall carbon nanotubes using PECVD technique: An efficient chemiresistor gas sensor

Highlights: • Uniform VA-SWCNTs have been grown on Fe/Si substrate using PECVD technique. • The SWCNTs sensor shows a considerable increase in resistance after exposure with NH₃. • The sensor response is quite fast. • The sensor recovery is observed about 80% at room temperature in few seconds. • No external excitation energy was supplied to get recovery of the sensor. In this work, the uniform and vertically aligned single wall carbon nanotubes (SWCNTs) have been grown on Iron (Fe) deposited Silicon (Si) substrate by plasma enhanced chemical vapor deposition (PECVD) technique at very low temperature of 550 °C. The as-grown samples of SWCNTS were characterized by field emission scanning electron microscope (FESEM), high resolution transmission electron microscope (HRTEM) and Raman spectrometer. SWCNT based chemiresistor gas sensing device was fabricated by making the proper gold contacts on the as-grown SWCNTs. The electrical conductance and sensor response of grown SWCNTs have been investigated. The fabricated SWCNT sensor was exposed to ammonia (NH₃) gas at 200 ppm in a self assembled apparatus. The sensor response was measured at room temperature which was discussed in terms of adsorption of NH₃ gas molecules on the surface of SWCNTs. The achieved results are used to develope a miniaturized gas sensor device for monitoring and control of environment pollutants.