Investigation of the Effect of ZnO Film Thickness over the Gas Sensor Developed for Sensing Carbon Monoxide

Abstract

Herein, a facile and inexpensive ZnO thin film‐based carbon monoxide gas sensor is fabricated using a solution‐process technique. To vary the thickness of ZnO thin films, the precursor solutions of two different molarities, 3 and 5 m, are spin coated over glass substrates. The 3 m ZnO thin‐film device demonstrates more than two times improvement in sensing response as compared to 5 m ZnO films, for 50 ppm carbon monoxide concentration. Additionally, the 3 m ZnO film is found to perform better for low carbon monoxide concentrations, whereas the 5 m ZnO film shows a linear response over a wider range of carbon monoxide concentrations. The gas sensing mechanism and the impact of film thickness on the performance of the device are thoroughly studied and discussed, which may open the doors for the design and development of facile and high‐sensitivity metal oxide‐based gas sensors.

A Mini-Review on Metal Oxide Semiconductor Gas Sensors for Carbon Monoxide Detection at Room Temperature

“…Infrared CO sensors have a large volume and high price. Compared with their counterpart like an electrochemical CO sensor, semiconductor CO sensors have several advantages such as low cost, high robustness, and a long lifetime, thus are widely applied in CO monitoring [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. Many semiconductors such as carbon nanotubes, metal oxides, and organic compounds have been studied for use in CO sensors [23][24][25][26].…”

“…Many semiconductors such as carbon nanotubes, metal oxides, and organic compounds have been studied for use in CO sensors [23][24][25][26]. Among all the semiconductor sensing materials, metal oxides are the cheapest and most stable ones [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. It is a trend to incorporate MOS CO sensors into mobile phones or other portable devices to facilitate CO measurement [27].…”