The Investigation On The Performance Of Metal Doped ZnO Based Relative Humidity Sensor

In recent years,due to the increasingly strict monitoring of humidity in living and industrial production,humidity sensors have been widely used and popularized.The performance of humidity sensors depends on the choice of humidity sensitive materials.Zinc oxide?ZnO?semiconductor material has good crystallinity,high electron hall mobility and good thermal stability,especially the controllability of the material,making it one of the most promising materials with low development cost and high humidity sensor performance.However,pure zinc oxide?ZnO?humidity sensitive materials still have problems in selectivity,stability and anti-interference ability.Therefore,in this study,ZnO was dropped with metal elements to improve the performance of zinc oxide humidity sensitive materials.The doping of metal elements can promote the formation of novel moisture sensitive materials with large specific surface area,high active sites and abundant oxygen vacancies in ZnO nano-semiconductor materials.In addition,the doping of metal elements can enhance the electrical properties of ZnO nano-semiconductor materials.Therefore,it has attracted great interest in the synthesis of new zinc oxide?ZnO?-based moisture sensitive materials,and has become the most popular material for developing low-cost,high-performance humidity sensors.Based on the above viewpoints,the ZnO nano-semiconductor materials have been successfully improved by using magnesium and gold nanoparticles?AuNPs?in the paper.The detail study summarized as follows:1.Mg-doped ZnO microspheres with high active sites and abundant oxygen vacancies were obtained by sol-gel method.After the analysis of morphology and structure of Mg-doped ZnO materials,it is known that Mg²⁺is successfully incorporated into the lattice of ZnO.The humidity sensitivity of black ZnO nanomaterials with different doping ratios was tested at room temperature.The results show that only Mg-doped ZnO?1.5mol%?nanomaterial exhibit about 4 orders of magnitude change in relative humidity of 11%to 95%RH,with good linearity and low humidity hysteresis?4.1%?,fast sensor recovery time?12 s?and response time?24 s?.In addition,the humidity mechanism of Mg-doped ZnO?1.5mol%?microspheres was analyzed by complex impedance spectroscopy,which provided a theoretical guidance for further optimization of humidity sensitive materials and device structure design.2.Nano-gold particles?AuNPs?modified black ZnO nanorods?6mL AuNPs?with high sensitivity and humidity sensing performance were successfully obtained by sol-gel method.The results of EDS and TEM shown that gold nanoparticles?AuNPs?are successfully combined with black ZnO?6mL AuNPs?.The vertical growth of AuNPs/ZnO?6mL AuNPs?nanorods was clearly observed by SEM,and the interior was interconnected frame space structure.Such a structure has a large specific surface area and many active sites so that water molecules can be rapidly transferred and transported.The nanomaterials of all AuNPs/ZnO were simply fabricated into resistive humidity sensitive devices,and their humidity sensitivity properties were studied under different humidity?11%RH to 95%RH?.The results show that all AuNPs/ZnO humidity sensors have faster response than pure ZnO humidity sensors,and the sensitivity of the best humidity sensitive?the impedance is about four orders of magnitude change?AuNPs/ZnO humidity sensor?6mL AuNPs?is three orders of magnitude higher than that of pure ZnO humidity sensors.Moreover,the humidity hysteresis is as low as 2.8%,and the response and recovery times are 32.6 s and 5.6 s,respectively.