Effect of electrode material on transport and chemical sensing characteristics of metal/carbon nanotube contacts

Abstract

In this paper, we report on the electrical transport characteristics and sensitivity to chemical exposure of single wall carbon nanotube devices fabricated on Pd, plasma-oxidized Pd, and Au electrodes. When the devices are exposed to vapors from ammonia, ethanol, and water, the response of current to each chemical is unique. However, there is essentially no difference in response between devices with different electrode materials. This finding suggests that for the chemical species tested in this study, the main interaction is on the nanotube or nanotube junction, and not on the effect stemming from electrode adsorption and the change in electrode work function.

Carbon Nanotube Gas and Vapor Sensors

“…reported device response to NH 3 with SiO‐passivated NTFET device contacts, and using their experimental data they calculated that NH 3 adsorption resulted in a donation of 0.04 electrons per molecule,48 which is in perfect agreement with the value that Lee and co‐workers calculated 25. Similarly, Jones et al 49. concluded that NTFET device response to NH 3 exposure resulted from charge transfer with the CNT.…”

Gas‐ und Dampfsensoren auf der Basis von Kohlenstoff‐Nanoröhren

“…Dies stimmt genau mit dem bereits von Lee und Mitarbeitern berechneten Wert überein 25. Jones et al 49. schlussfolgerten ebenfalls, dass die Reaktion des NTFET bei NH 3 ‐Exposition aus einem Ladungstransfer mit der CNT resultiert.…”

Application of plasma modified multi-wall carbon nanotubes to ethanol vapor detection

“…Comparing with other CNT-based ethanol sensors, the best sensor response to 500 ppm ethanol at room temperature is 1.12 [9] and 1.07 [13], respectively. When the sensing temperature raises up to 165 • C, the sensor response increases to 1.38 [8].…”

“…Many important applications have been demonstrated, and both CNT-based [5][6][7][8][9][10][11][12][13] and CNT-doped [14][15][16][17][18][19][20] gas sensors were received considerable attention because of their nanometer hollow geometry, high specific surface area, high electron mobility, surface modification, and functionalization.…”

“…CNT-based ethanol sensors may work at room temperature and have a quite low detection limit; however, they exhibit a lower sensitivity due to fewer percentages of semiconducting nanotubes that can be modulated by gas molecules. Besides, the recovery time of CNT-based ethanol sensors is actually long because of the strong adsorption between CNTs and gas molecules [8,9]. Some kinds of surface modifications, including acid treatment [23], annealing [23], and oxygen plasma treatment [24,25] have been reported for enhancing the sensing sensitivity.…”