Study On Pore Size And Zinc Oxide Thickness Effect Of Zinc Oxide Gas Sensor Based On AAO Template

Recent years,with people's awareness of environmental protection and great concern for health issues,the gas sensor,which is used to simulate the mechanism of human olfactory system,plays a significance role in people's production and daily life.And it's widely used in indoor gas sensor detection,food safety,industrial safety management,disease diagnosis and other fields.The high performance gas sensors are in great demand with the development of semiconductor technology and integrated circuits.Zinc oxide(ZnO)is one of the best gas-sensitive materials because of its higher-conductivity,unique physical and chemical properties,lower cost and be compatibility with standard CMOS process.It is known that the gas sensor's performance is closely related to the materials identification ability,conversion ability and effective utilization.A variety of methods have adopted to improve the performance of ZnO gas sensors,such as element doping,different structure preparation,and etc.However,a rational design for porous structure and large surface to volume ratio materials is one of the effective ways to improve performance.And the nao-ZnO gas sensor based on anodic aluminum oxide(AAO)template has an important effect on the sensitivity improvement due to its larger surface to volume,richer surface active sites,higher gas diffusion ability and accurate shape controlling.This paper focuses on the sensitivity improvement for ZnO gas sensor based on AAO template.On the basis of elaborating the sensing principle of the gas sensor,the physical parameter and surface state prior models within the semiconductor simulation software SILVACO are adopted to study the influence of device physical parameters on the sensitivity of this gas sensor,which includes tube diameter and zinc oxide's thickness.Simulation results indicates that among the porous nano-ZnO gas sensor with three different diameter sizes of 500 nm,700nm and 900 nm prepared by AAO template method,the largest diameter size of 900 nm has the highest sensitivity to nitrogen dioxide gas at room temperature,and all of them have identical cycle,ZnO thickness,depth and trap density.The corresponding sensitivity increases from 1.59 to 2.57 as the tube diameter increases from 500 nm to 900 nm for 3×3 matrix.Meanwhile,the increased total potential distribution and more uniform current density distribution in 3D surface is observed together with the calculated surface to volume ratio of 2.1?m-1,3.334?m-1,5.04?m-1 when the diameter is enlarged.And the experimental results are consistent with the simulation results.Besides,compared to surface thickness of zinc oxide,the AAO section has a greater effect on the sensitivity of gas sensor.And the thickness is thinner,the high sensitivity is.Therefore,in the actual device preparation,the tube size of the gas sensor should be made as large as possible and the thickness of zinc oxide in AAO section should be thinner to obtain a higher sensitivity.In addition,the actual device is composed of millions of holes and the depth of gas sensor is greater,thus its sensitivity will be higher than the simulation results.Although the simulation results cannot be perfectly matched with the experimental results,we can obtain a more accurate preparation direction and provide guidance for the performance improvement of the device in the process of studying the effect of its physical parameters on simulation results.