Gas Sensitivity Of ITO Film Based On SPR Technology

Indium tin oxide?ITO?is an n-type semiconductor material,compared with other metal oxides,ITO has the characteristics of corrosion resistance,high light transmittance,good electrical conductivity,etc.,widely used in the field of screen display.Both In₂O₃ and SnO₂ are gas-sensitive materials,so ITO can be used as gas-sensitive materials in the field of gas-sensitive sensors.Surface Plasma Resonance?SPR?is an optical phenomenon produced by the interaction of light with the dielectric/metal interface.Because of its high precision,high sensitivity,no damage to the test object and no need to mark,SPR technology has been widely used in life science research,environmental monitoring,gas sensing and other fields.In this paper,the SPR characteristic curves of Au,Ag and Al metals are compared and analyzed through simulation and testing,and the best SPR characteristic of Ag film is obtained.Ag/ITO composite films were prepared on Ag films,and the SPR properties of Ag/ITO composite films were studied.ITO film can improve the sensing characteristics and prevent Ag film oxidation.The preparation technology and SPR characteristics of Ag/ITO films were obtained by simulation and experiment.When the thickness of Ag and ITO films was 41.23nm and 14.84nm respectively,the SPR performance was the best.The gas sensitivity of formaldehyde,nitrogen dioxide and ammonia was tested by using Ag/ITO composite film.The results showed that the formaldehyde concentration ranged from 0 to 218.95mg/L,the sensitivity was 5.65x10^-3o/?mg/L?,and the minimum resolution was 1.77x10^-1mg/L.NO₂ concentration in 0-276.13 mg/L range,sensitivity of 2.82x10^-2o/?mg/L?,minimum resolution of 3.55x10^-22 mg/L.Ammonia concentration ranged from 0 to 242.17mg/L,with a sensitivity of 1.19x10^-2o/?mg/L?,and the minimum distinguishable concentration was 8.4x10^-2mg/L.Compared with formaldehyde and ammonia,Ag/ITO films have better SPR performance for nitrogen dioxide gas.