Preparation And Study Of SnO₂ Nanoparticle Thin Film Room Temperature NO₂ Gas Sensor With High Sensitivity

At present,the NO₂ gas content in the air was gradually increasing,which affected seriously people’s health and the natural environment.Therefore,we needed to use NO₂gas sensors to monitor the NO₂ gas content in the air to safeguarded people’s healthy life.The commonly used semiconductor resistive gas sensor had excellent gas sensing performance,but its high working temperature would reduce the stability of the gas sensor and increased the power consumption of gas sensor,and had potential risks.Therefore,we should try our best to develop NO₂ gas sensors with energy efficient,good stability,high sensitivity and working normally at room temperature.The research subject of this paper was SnO₂ nanoparticle thin film gas sensor,and the effect of continuous ultraviolet and periodic ultraviolet light on the performance of SnO₂nanoparticle thin film room temperature NO₂ gas sensor was explored,and the SnO₂nanoparticle thin film room temperature NO₂ gas sensor with high sensitivity was obtained through parameter optimization.Firstly,we synthesized the SnO₂ precursor and fabricated the SnO₂ nanoparticle films on various substrates by spin coating and annealing.Various characterization methods showed that the prepared SnO₂ nanoparticle film had the advantages of small particle size,high oxygen vacancy concentration and controllable thickness.The responsivity of the SnO₂ nanoparticle film gas sensor was 19.2 to 5 ppm NO₂,the reaction time and the recovery time was 385 s and 1396 s in the dark at room temperature.Then we studied the effect of persistent ultraviolet light on the gas sensing performance of SnO₂ nanoparticle thin film NO₂ gas sensor.We explored the influence of ultraviolet light intensity on the sensitivity of gas sensor.The results revealed that within the light intensity range of our measured,the lower the UV intensity,the higher the sensitivity of the device.That was because the relative adsorption amount of NO₂molecules on the semiconductor surface increased when light intensity gradually decreased.Under the irradiation of 0.9μW/cm² continuous UV light,the responsivity of SnO₂ nanoparticle film NO₂ gas sensor to 5 ppm NO₂ gas was 1138.1,the reaction time and the recovery time was 125 s and 72 s.The consequences were compared with the previous results,the responsivity increased by nearly 60 times,the response time was 1/3 of the original,and the recovery time was 1/20 of the original.Finally,we studied the effect of periodic ultraviolet light on the gas sensing performance of SnO₂ nanoparticle thin film NO₂ gas sensor.The results showed that the sensitivity of the device to 5 ppm NO₂ gas could reach 10⁶ under the irradiation of430μW/cm² periodic ultraviolet light,which was three orders of magnitude higher than that in continuous UV mode,and five orders of magnitude higher than that in dark.The reason of periodic UV light controlling gas sensor was explained in detail by using the model of crystal plane barrier and the theoretical calculation.