Field emission model of carbon nanotubes to simulate gas breakdown in ionization gas sensor

Abstract

A new field emission model of carbon nanotubes (CNTs) to simulate gas detection mechanism in CNT based ionization gas sensor has been developed. The new model consists of three modules which are combined together and embedded in the standard particle-in-cell/Monte Carlo collision codes. The functionality of the enhanced model is checked by varying the gas pressure and gap spacing in the simulations. From the results, around one order of magnitude decrease in the breakdown voltages and two orders of magnitude faster response time is observed. The lowest breakdown voltages are observed when intertube spacing is equal to height of the nanotube. The field enhancement factor β is calculated from our model and compared with the β of the well established model. The closeness among the values of β validates the performance of our field emission model. Furthermore, the β of our model is compared with the β of the existing ionization gas sensors. It was found that the β of our sensor is around 3 times better than the β of the gold nanowire based ionization gas sensor and 28 times better than the β of the other CNT based ionization gas sensor. These results suggest that by properly controlling the growth of CNT structures, an optimized CNT based ionization gas sensor can be realized.

Metal Decoration and Magnetic Field Effect on the Electrical Breakdown Voltage for ZnO Nanorods Gas Ionization Sensor

“…Electron impact ionization (EII) and field ionization (FI) processes were, respectively, proposed for nanomaterial configured as a cathode (Huang et al, 2009;Chivu and Kahrizi, 2013;Mahmood et al, 2013) and an anode (Longwitz et al, 2001;Huang et al, 2009). If the nanorod was biased as a cathode, electrons would be extracted form cathode and in turn be accelerated and impact with gas molecular.…”

“…If the nanorod was biased as a cathode, electrons would be extracted form cathode and in turn be accelerated and impact with gas molecular. Then the gas molecular would be ionized by electron bombardment (Longwitz et al, 2001;Huang et al, 2009;Chivu and Kahrizi, 2013;Mahmood et al, 2013). If the nanorod was biased as an anode, gases would be ionized near the surface of nanotips by strong field extraction of the most loosely bound electrons from gas molecules (Longwitz et al, 2001).…”