Arc-discharge deposition of SWCNTs over SnO 2 nanowires for highly sensitive NO 2 gas sensor

• Published in: Advances in natural sciences. Nanoscience and nanotechnology Vol. 13; no. 3; p. 35007
• Main Authors: Thi Xuan, Chu, Hung, Chu Manh, Van Duy, Nguyen, Ngoc, Trinh Minh, Thi Minh Nguyet, Quan, Hoa, Nguyen Duc
• Format: Journal Article
• Language: English
• Published: 01.09.2022
• ISSN: 2043-6262; 2043-6262
• DOI: 10.1088/2043-6262/ac87a3

Abstract The air pollution caused by the emission of NO 2 from vehicles in large cities is threatening human health. Thus, a highly sensitive gas sensor is required to monitor this gas. Here, we introduced the arc-discharge deposition of single-walled carbon nanotubes (SWCNTs) over SnO 2 nanowires for highly sensitive NO 2 gas sensors. The high-quality SnO 2 nanowires were grown on-chip on interdigital Pt electrodes, whereas the SWCNTs were deposited by in situ arc-discharge method. To form the heterojunction between SnO 2 nanowires and SWCNTs film, we controlled the length of the SnO 2 nanowires to avoid bridging of the two electrode fingers while covering the entire surface of Pt electrodes. The SWCNTs were deposited through a shadow mask to ensure the contact between the SWCNTs and SnO 2 nanowires but not the Pt electrodes. Electrical measurements confirmed the formation of non-linear contact between SnO 2 nanowires and SWCNTs because of the n-p heterojunction. An increment in resistance (decrease in resistance) of the sensor was observed when measured in NO 2 gas, indicating the good response characteristics of the device based on heterojunction between SnO 2 nanowires and SWCNTs. In addition, gas-sensing measurement at different temperatures indicated that the fabricated sensor could detect low concentrations of NO 2 gas in the range of 1–10 ppm, with response values of 20–80. The results demonstrated that the arc-discharge deposition of SWCNTs over SnO 2 nanowires is effective for the fabrication of highly sensitive NO 2 gas sensors.