| Summary: | 碩士 === 國立屏東科技大學 === 材料工程研究所 === 101 === In the current study, MEMS ( Micro-Electro-Mechanical Systems ) technologies are used to fabricate micro VOCs gas sensors, which structure contains thin film sensing layer and platinum sensing electrode on Al2O3 substrates. The make E-beam is used to make platinum electrodes and RF sputtering deposition is used to the sensing films. Finally, annealing is used to obtain pore structure for enhancing the sensitivity. The experimental results show that a redox reaction occurs when the volatile gases contact the sensing layer at working temperature, and the resistance variation can be measure due to the changes of volatile gas concentration. In this study, two gas sensing layers, of NiO and WO3, get porous structure at 180 W and 160 W RF sputtering power with 300 ° C sputtering temperature and 400℃ annealing temperature, respectively. The porous structure can increase sensing response and sensitivity. The experimental results show that concentration of toluene from 0 ppm to 1 ppm , the average variation rate of TVOC gas sensor is 3.53% / ppm, and from 1 ppm to 2.5 ppm it is 0.93% / ppm. The resistance stability is 0.33 kΩ/sec at 300°C sensitivity of formaldehyde gas sensor is 45 Ω/0.1 ppm, the resistance stability id less than 30 Ω/10min. The micro volatile organic gas sensors show high sensitivity, good stability and well repeatability.
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