Ultrasonic Spray-microwave Pyrolysis Preparation Of ITO Transparent Conductive Film

ITO?In₂O₃ and SnO₂ mass ratio of 9:1?thin film is an important high degenerate N-type semiconductor materials.Because of the low resistivity,high transmittance,high mechanical hardness,good chemical stability,excellent adhesion,etc.,ITO thin film is widely used in the field of flat panel display,transportation devices,protective materials,luminous stealth materials,high-rise buildings,solar cell,and sensitive devices,etc.Some literatures have shown that in order to produce high quality ITO film,some unfavorable factors such as expensive equipment,complicated procedures,and long production cycle,etc.,are really existed in some production processing of ITO thin films.In this paper,a method of direct deposition of ITO transparent conductive thin films by spray pyrolysis combined with microwave heating have been introduced.The main research contents include:?1?The preparation method,the thermodynamic principle of thin film deposition reaction,and the TG-DSC of the precursor materials was analyzed.It was found that the starting pyrolysis temperatures of tin tetrachloride?395.1 K?and indium trichloride?553 K?were different,which provided the theoretical basis for the following temperature experiments.The heating rate?max 91 ?/min?of the substrate/base under microwave heat source was investigated.The dielectric constant of the precursor solution is slightly smaller than that of water,but its dielectric loss tangent tan?=0.3725 is larger than that of water,which showed excellent microwave absorption properties for the chloride precursors.?2?The effects of microwave pyrolysis temperature,precursor solution concentration,substrate and nozzle distance on the structure and properties of ITO thin films were studied.The optical and electrical properties of the prepared films using the traditional heat source and microwave heat source were compared.The results showed that the ITO thin films was uniform and smooth at 500? of microwave pyrolysis temperature,0.05 mol/L of precursor concentration,and t 20 cm of the distance between the substrate and the nozzle.Meanwhile,at the preparing conditions,the size distribution of ITO grains in the film was narrow?16?32 nm?,and the visible light transmittance and the resistivity was 96.55%and 2.28×1-4?·cm.Respectively,which showed better surface morphology,one order of magnitude lower resistivity compared to the ITO thin films prepared by traditional spray pyrolysis.?3?The effect of Sn doping on the microstructure and properties of indium oxide films was also investigated.It was found that Sn dopant can reduce the resistivity of indium oxide thin films by two orders of magnitude and improve the film transmittance of 3.85%in parallel.Finally,the microstructure and surface roughness of the films were optimized,and the optimum tin oxide doping was in the range of 5%and 15%.In a word,ITO thin film was successfully prepared by ultrasonic spray combined with microwave pyrolysis method without post processing.The obtained films demonstrated excellent morphology,optical and electrical properties.This method can also be used for the preparation of other films.