Fabrication of ozone gas sensor based on FeOOH/single walled carbon nanotube-modified field effect transistor

Abstract

A novel ozone (O₃) sensor is fabricated using commercial metal oxide field effect transistor (MOSFET), modified with single-walled carbon nanotubes (SWCNTs). In this study, integrated circuit (IC: BS250) was selected as the selective probe for O₃ detection. For this purpose, a plastic cover on the surface of the drain was drilled to bare the drain surface, followed by its modification with nitrogen and sulfur-functionalized SWCNTs by chemical vapor deposition (CVD) process. The CVD-synthesized SWCNTs were then electrodeposited with FeOOH nanostructures. According to the figures of merit, the fabricated sensor gave a linear output from 20 to 450 parts per billion (ppb). Detection limit was also 4.1 ppb. Relative standard deviation (RSD) for seven replicate analyses was 3.61%. Based on 90% of maximum response (t₉₀), the response time was ∼1.5 min. Calibration sensitivity was measured to 1.3 mV/ppb. No interference was observed, when introducing at least 500 folds of interferences of gaseous species such as H₂O, HCl, H₂S, O₂, H₂, CO, CO₂, NO₂, SO₂, Cl₂, C₂H₂, CH₄ and volatile organic compounds (VOCs) to 250 ppb of O₃ solution. Reliability of the sensor was also evaluated via determination of O₃ in different air samples.

Keywords:

• O₃ gas sensor
• FeOOH nanostructures
• field effect transistor
• carbon nanotubes

Acknowledgement

The authors wish to acknowledge the support of this work by Shiraz University Research Council.