Preparation And Research Of AZO-TFT On Flexible Substrate

In recent years,the demand for flexible electronic technology has significantly increased in various industries.As a new generation of display technology,flexible display has great application prospects in emerging fields such as foldable phones and intelligent wearable devices.Thin film transistor（TFT）,as a driver for flexible displays,its electrical performance is crucial.Metal oxide thin film transistors have advantages such as high mobility and low process temperature,making them very suitable for preparing flexible display driver devices.Among them,indium gallium zinc oxide TFT（IGZO TFT）is the current mainstream technology,but the content of indium in the earth’s crust is very low and expensive,As a result,this technology cannot meet the requirements of high-performance and low-cost devices for the new generation of displays.Therefore,studying indium oxide free TFT technology suitable for flexible displays is of great research significance.The low-cost aluminum doped zinc oxide film（AZO）is one of the low-cost and feasible alternatives to IGZO.In this study,AZO-TFT devices were prepared on flexible polyimide（PI）substrates at room temperature by radio frequency magnetron sputtering.Each functional layer of the device does not contain trace element.The effects of thickness,argon oxygen ratio,and Al sputtering power on the properties of AZO films were systematically studied,and the electrical properties of flexible AZO-TFT were studied and optimized,To meet the demand of flexible display technology for low-temperature,low-cost,and high-performance flexible TFTs.（1）The effect of film thickness on the properties of AZO thin films and the electrical performance of flexible AZO-TFT devices was studied.AZO thin films were prepared on flexible PI substrates at room temperature by magnetron sputtering technology.The thickness of the films was adjusted to 53 nm,62 nm,79 nm and 94nm by changing the sputtering time,and flexible AZO-TFT devices were prepared using them as active layers.Research has found that AZO thin films become uniformly dense with increasing thickness.When the thickness of AZO thin films is79 nm,AZO-TFT devices prepared on flexible substrates exhibit relatively excellent electrical performance,with a current switching ratio of 6.62×10⁴,subthreshold swing1.31 V·dec^-1,mobility 2.21 cm²·（V·s）^-1.（2）The effect of sputtering argon oxygen ratio on the properties of AZO thin films and the electrical performance of flexible AZO-TFT devices was studied.AZO thin films were deposited on flexible PI substrates by Magnetron sputtering at room temperature,and the argon oxygen ratios were 100:0,95:5,90:10,and 80:20,respectively.Research has found that when the argon oxygen ratio is 90:10,the grain growth is good,the film surface is uniform and dense,the root mean square roughness is the lowest,the device mobility is 0.74 cm²·（V·s）^-1,and the switch ratio is 7.45×10³,subthreshold swing is 1.74 V·dec^-1,and threshold voltage is 7.35 V.（3）The effect of Al target sputtering power on the properties of AZO thin films and the electrical performance of flexible AZO-TFT devices was studied.AZO thin films were prepared on flexible PI substrates by magnetron sputtering at room temperature,keeping the sputtering power of Zn O target unchanged.Research has shown that when the sputtering power of Al target material is 15 W,the surface morphology of the thin film is better,the density is higher,and the roughness measured by AFM is also the lowest,at 1.333 nm.The threshold voltage is 10.22 V,and the current switching ratio is 5.23×10⁵,subthreshold swing 0.39 V·dec^-1,mobility0.031 cm²·（V·s）^-1.