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Preparation And Acetone Gas Sensing Property Study Of ZnO Thick Film

Posted on:2018-06-24Degree:MasterType:Thesis
Country:ChinaCandidate:X H GuoFull Text:PDF
GTID:2428330596957833Subject:Microelectronics and Solid State Electronics
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ZnO has been extensively investigated for gas sensors because of its non-toxic,low cost and stability in physical and chemical property.However the gas sensors based pure ZnO have some disadvantages still,such as high operating temperature,poor selectivity,low stability and long response time and recovery time.Thence,a variety of approaches have been provided to improve the gas sensing property of ZnO.And the method by doping is more popular.In this work,ZnO nanoparticles doped with Al2O3 were prepared by sol-gel method.Materials were characterized via XRD and SEM and sensing properties were tested.The effect of doping content,operating temperature,annealing temperature and UV light excitation on sensing property and the effect of aging temperature,relative humidity on sensors stability were investigated.Meanwhile,the sensing mechanism was discussed.The work contains:ZnO nanoparticles doped with Al2O3?i.e.,0,2.96,4.96,and 6.96wt%in mass?were prepared by a sol-gel method and the optimum preparation processes were confirmed.The materials were characterized by XRD and SEM.The results showed that all of the samples were wurtzite phase and there were no other peaks related to dopants.However,the doping of Al2O3 led to the porous surface and small gain size of ZnO.The sensors were tested and aged.The results indicated that the addition of Al2O3promoted the sensing response and stability of ZnO nanoparticles.The optimum performance was obtained by 4.96wt%Al2O3-ZnO annealed at 700oC.The response to acetone?100ppm?was 29.24 at a low operating temperature of 64oC,and the response time and recovery time were both 2s.Even when the concentration of acetone was 10ppm,there was an excellent response of 3.23.Meanwhile,when the aging temperature was close to its optimum operating temperature,the stabilities of sensors were highest.And with the increase of aging humidity at a range of 30-70%RH,the stabilities of sensors had a trend to enhance.The sensing properties to acetone were investigated with an irradiation of UV.The results demonstrated that optical excitation with UV irradiation greatly enhanced the sensing response.The sensitivity of 4.96wt%Al2O3-ZnO to acetone?1000ppm?can reach up to 305.14 from 242.81 with a highest enhancement of 26%.The sensing mechanism was deeply discussed combined with the grain boundary barrier model,photocatalytic theory and the UV-Vis spectroscopy.
Keywords/Search Tags:Zinc oxide, Aluminum oxide doping, Sol-gel, Acetone sensing property, Gas sensing mechanism
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