Preparation And Photoelectric Properties Of Ta Doped SnO₂ Thin Films And Multilayer Thin Films

In recent years,with the rapid development of smartphones,ipad,organic light emitting diode,low-E glass,solar cells and other industries,the development and application of transparent conductive oxide（TCO）is becoming more and more popular with the scientists.As the basis of photoelectric devices,the cost and performance of transparent conductive oxide（TCO）have great significance to the development of the smart terminal.The existing TCO materials mainly include ITO,but ITO has many disadvantages such as expensive price,insufficient reserves and unsuitable for flexible film.Because of these reasons,many countries are trying to develop a new transparent conductive film material without indium through a series of scientific research programs.Ta-doped SnO₂（TTO）and SnO₂/Ag/SnO₂ thin films were prepared by High Target Utilisation Sputtering（HiTUS）form PQL company on a common glass slide substrate.The surface morphology and the proportion of doping elements were investigated by SEM and TEM.The element valence and material status on the surface were investigated by XPS.UV-3600 were used to test the transmittance in the visible range of the film.The Lake shore 8400 and semiconductor properties tester were used to test electrical performance.The conclusions are as follows:1 Ta doped SnO₂ films（TTO）（1）The oxygen flow will significantly affect the crystal structure of the film.When the oxygen flow is low,the film presents the amorphous and nanocrystalline state.In addition,the annealing of film have a big impact on crystal structure,when annealing temperature is below 250℃,film presents the amorphous and nanocrystalline state.When annealing temperature is above 450°℃,film can present a tin oxide crystals of rutile phase.（2）The oxygen flow and annealing temperature have a great influence on the transmittance of the film.The transmittance of the film increases with the increase of oxygen flow.When the oxygen flow rate is above 4 sccm,the transmittance of the films is over 70%.While increasing the annealing temperature also increases the transmittance of the film in the visible light range.After annealing under the condition of 250℃and 450℃for 30 min,the transmittance of films increases 90%and 93%respectively.（3）Oxygen flow and annealing temperature also significantly affect the electrical properties of the films.With the increase of oxygen flow,the electrical properties of the films showed a trend of decreasing first,and the electrochemical properties of TTO films reached the optimal value at oxygen flow rate was 5 sccm.Proper annealing temperature also can improve the electrical performance of thin film,under 270℃electrical properties of films increased with the increase of annealing temperature increases.In more than 270℃electrical performance and decreased with the increase of annealing temperature.2 SnO₂/Ag/SnO₂ multilayer film（1）The microstructure of SnO₂/Ag/SnO₂ thin film under different silver thickness is different.When the silver layer thickness in under 6 nm,the silver layer is mainly isolated island distribution.After the silver layer thickness is more than 6nm,the distribution of the silver layer from the island isolation into a continuous planar distribution.（2）As the thickness of the silver layer increases,the optical performance of the film decreases gradually.When the silver thickness in the middle layer is 2nm,the average transmittance of thin film can reach 90%.And when the silver thickness in the middle layer is 6nm and 12 nm,the average transmittance drop to 86%and 86%respectively.（3）With the increase of the thickness of the silver layer,the electrical properties of the films gradually increased.When the thickness of the silver layer is 2 nm,the resistivitty of the film is 1×10^-2Ω?cm,and hall mobility is 6.58 cm²/V^-1s^-1.When the thickness of the silver layer is 6 nm,the resistivitty of the film is 8.41×10^-5Ω?cm,and hall mobility is12.3 cm²/V^-1s^-1.When the thickness of the silver layer is 12 nm,the resistivitty of the film is 4.52×10^-5Ω?cm,and hall mobility is 17.7 cm²/V^-1s^-1.（4）The figure of merit is a comprehensive index to evaluate the optical properties and electrical properties of thin films.When the sliver thickness is 6 nm,the film has the highest figure of merit（FOM）,which can reach 8.7×10^-2Ω^-1.When the thickness of the silver layer is less than 4 nm,the conductivity of the film restricts the improvement of its figure of merit.When the thickness of the silver layer is greater than 4 nm,the transmittance of the film restricts the improvement of its figure of merit.