Institute Of Al Doped ZnO Sensor

Zinc oxide belongs to the semiconductor material,and its metal oxide with wide forbidden wide.Chemical and physical properties of zinc oxide is stable,its raw materials are abundant,the preparation cost is cheap,and zinc oxide has good gas sensitive,photocatalytic performance,therefore zinc oxide materials are used in many fields.Nanopowder of aluminum doped zinc oxide is prepared by sol gel method with different doping concentration,and prepare of gas sensor.The principal activities were as follows:1.Anhydrous ethanol and deionized water were mixed in a 1:1 ratio to prepare solvent,using zinc acetate,sodium hydroxide,aluminum nitrate as raw materials,pure zinc and aluminum doped zinc oxide nanopowder were prepared by sol gel method with different doping amount 0wt.%,2.98 wt.%,4.98 wt.%,6.98 wt.%,respectively.zinc oxide gas sensor was prepared by dip-coating method.2.Absorption and transmission spectra of powder sample were obtained by uv-vis spectrophotometer,and calculate the band gap width of sample by extrapolation method.After it was found that absorption strength of doped zinc oxide increased in the visible and ultraviolet band,the strength of absorption in the uv band is more obvious;In more than 450 nm band,transmittance of several samples were very high,above 85%.3.Through the characterization of XRD,SEM and the corresponding gas sensitive test,we got: With the increase of doping amount,arrange became more loose,crystalline size decreases.The changes in the morphology was good for gas adsorption,thus the gas-sensing properties of sample increased.As the annealing temperature rising,the crystalline size increases gradually,which corresponded particle size of the XRD results.4.Through gas sensor test,the selectivity to acetone of samples is best,sensitivity of doping zinc oxide was much higher than the pure,response-recovery time reduced greatly,and operating temperature dropped.5.Especially the samples with doping amount of 4.98 wt.%,its sensitivity was up to 14075,the response-recover time were 3s and 1s,respectively,working temperature was down to about 100℃.6.We determined the best preparation technology of Al doped ZnO through the experimental results and analysis:the preparation of pH value of 7,the best doping amount of 4.98 wt.%,the best annealing temperature was 700℃,the best working temperature was 100℃.And further analysis the mechanism how doping and ultraviolet excitation increase gas sensor performance of zinc oxide.