ZnO thin film based ethanol sensor derived by RF sputtering technique

Abstract

This paper described the design, fabrication, and test results of Zinc Oxide (ZnO) thin films based ethanol (C2H5OH) sensor. Pure ZnO (c- axis oriented) thin films was prepared by RF magnetron sputtering techniques at room temperature on Silicon (Si)/Silicon dioxide (SiO2)substrate for gas sensing applications. Along with the ZnO thin film, Pt micro-heater, platinum resistance thermometer (PRT) and interdigited gold (Au) electrodes were also fabricated verticallyto make a complete C2H5OH sensor device. The layout design of platinum(Pt) microheater and PRT along with the interdigited electrodes is performed by the computor tool L-EDIT. The thermo-mechanical analysis of micr-heater was performed by the multi-physics simulator ANSYS. The deposited ZnO thin film is annealed at different temperatures in the range of 250 °C to 450 °C. The properties of annealed ZnO thin film was analyzed by using various charactirization techniques such as surface profilometer, XRD, EDX and SEM. A measurement set-up was also developed to measure the performance of Pt micro heater and the sensitivity of the sensor at differnet concentration of C2H5OH. The highest sensitivity of C2H5OH sensor was achieved at the operating temperature of 350 °C. The Ethanol sensor shows good performance in terms of stability, sensitivity, recovery, response, reversibility and repeatability in the concentration of C2H5OH ranging from 50 ppm to 200 ppm.