Sensing Mechanisms for Carbon Nanotube Based NH3 Gas Detection

Journal Article · Tue Mar 31 04:00:00 EDT 2009 · Nano Letters, 9(4):1626-1630

DOI:https://doi.org/10.1021/nl803930w· OSTI ID:1001533

Peng, Ning; Zhang, Qing; Chow, Chee L; Tan, Ooi K; Marzari, Nicola N

There has been an argument on carbon nanotube (CNT) based gas detectors with a field-effect transistor (FET) geometry: do the response signals result from charge transfer between adsorbed gas molecules and the CNT channel and/or from the gas species induced Schottky barrier modulation at the CNT/metal contacts? To differentiate the sensing mechanisms, we employed three CNTFET structures, i.e., (1) the entire CNT channel and CNT/electrode contacts are accessible to NH3 gas; (2) the CNT/electrode contacts are passivated with a Si3N4 thin film, leaving the CNT channel open to the gas and, in contrast, (3) the CNT channel is covered with the film, while the contacts are open to the gas. We suggest that the Schottky barrier modulation at the contacts is the dominant mechanism from room temperature to 150°C. At higher temperatures, the charge transfer process contributes to the response signals. There is a clear evidence that the adsorption of NH3 on the CNT channel is facilitated by environmental oxygen.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1001533
• Journal Information: Nano Letters, 9(4):1626-1630, Journal Name: Nano Letters, 9(4):1626-1630 Journal Issue: 4 Vol. 9
• Country of Publication: United States
• Language: English

Related Subjects

77 NANOSCIENCE AND NANOTECHNOLOGY
ADSORPTION
CARBON
DETECTION
Environmental Molecular Sciences Laboratory
FIELD EFFECT TRANSISTORS
GEOMETRY
MODULATION
NANOTUBES
OXYGEN
THIN FILMS