Construction And Sensitive Mechanism Of Metal Oxide Semiconductor Micro Gas Senso

Gas sensors play an important role in our daily life,and their typical applications include environmental monitoring,toxic gas detection,and industrial processes.Among various gas sensors,gas sensors based on metal oxide semiconductor（MOS）have been widely studied because of their high response,low cost,environmental friendliness and portability.At present,the preparation process of gas sensor sensitive layer is usually completed by coating,and most of them are thick film gas sensors.Thick film sensors not only have the disadvantages of low sensitivity,slow response and high requirements for working temperature,but also greatly limit the application range of gas sensors in application;At the same time,due to the complex sensing process of thick film devices,there are often multiple factors working together,so it is difficult to explore the sensing mechanism of the material itself.Based on the above research status,we will focus on the construction of thin film and single nanowire micro gas sensors,modify the surface of the materials by constructing heterojunctions and doping precious metals,improve the sensing performance of the materials,and deeply study the sensing mechanism.The main research contents of the paper are as follows:（1）Using atomic layer deposition（ALD）technology,we designed Ni O/In₂O₃heterogeneous films with periodic macroporous structure,which has great potential in the detection of NO₂ at low temperature.This strategy can effectively control the oxygen vacancy concentration and the formation of p-n heterojunction in In₂O₃/Ni O hybrid films,which can affect the surface chemical and electrical properties of the sensing films.The response of the modified In₂O₃/Ni O thin film sensor to 10ppm NO₂ at relatively low operating temperature（145 ^oC）is up to 532.2,which is 26 times higher than that of the initial In₂O₃.In addition,the sensor also achieved an ultra-low detection limit of 6.9 ppb,which exceeded the previous reports of most MOS sensors.（2）In this work,we employed a seed-assisted hydrothermal method to grow ultralong ZnO nanowires and functionalized the surface of ZnO with trace amounts of Pt particles by ALD and dipping methods,to constructing a single ZnO@Pt nanowire gas sensor.The effect of Pt deposition content and particle size on the gas sensing performance of the sensor was investigated by the controlled variable method.The research results show that the sensing performance of the ZnO@Pt sensor for NO₂ is significantly improved after depositing an appropriate amount of Pt by ALD,the optimal operating temperature is reduced from 310 ^oC（ZnO）to 210 ^oC,the low detection limit is 13.6 ppb and the response/recovery time is shortened to 12.8 s/21.8 s.On the basis of determining the optimal deposition content,the influence of Pt particle size on gas sensing performance is further explored.It is found that the sensor has the best response when the particle diameter is 3nm.