Preparation And Study Of IGZO-TFT Based On Anodic Oxidation

Amorphous Indium Gallium Zinc Oxide Thin Film Transistor?a-IGZO TFT?with high mobility,good homogeneity and can be transparency and flexibility,often used for large-scale preparation and flexible displays,has huge development potential in the display area.In this paper,according to the characteristics of anodizing growth of aluminum oxide insulation layer on metal aluminum and the characteristics of high voltage resistance of inorganic insulation layer,the method of anodizing is studied to optimize the leakage current and main performance of devices.The characteristics of the insulation layer and the active layer are studied.In the experiment,the insulation layer of TFT device is studied firstly.In this paper,four different anodic oxidation electrolysis solutions and five different anodic oxidation processes were used to prepare alumina films,and a-IGZO films were prepared by different oxygen partial pressure and sputtering power.In order to study the optimization of leakage current by anodic oxidation compared with other processes,a TFT device with Polymethyl Methacrylate?PMMA?as the insulating layer under different processes was prepared for comparative experiment.Since the performance of the device is not only determined by the insulation layer,the device is prepared under different anodic oxidation processes to optimize the TFT device.Experiments found that due to the electrolyte solution determines the type of the anodic oxidation film,the acid solution to generate more pass,neutral and alkaline solution generation type barriers,it was found that the device is a neutral solution is better than acid solution under the device,carrier mobility increased 12 times,current switch,increased 2.7 times threshold voltage reduced 2V,the threshold swing reduced 2.1V/dec.The duration of the constant current mode in the anodic oxidation process would affect the dissolution degree of the first stage of anodic oxidation of the film.The experiment found that the duration was 1200s,the performance of the device was the best,the carrier mobility increased by 31%,the current switch ratio did not increase significantly,the threshold voltage decreased by 0.2V,and the sub-threshold swing amplitude decreased by 0.8V/dec.The off-state current of the best device under different anodic oxidation processes is 1.0×10^-8,the current switch ratio reaches 8.0×10³,the carrier mobility reaches the highest 2.52cm²/V·s,the minimum threshold voltage is 3.9V,and the sub-threshold swing amplitude is 3.6V/dec.Because of alumina film preparation in aqueous environment,membrane surface morphology will affect device performance,experimental preparation composite insulation device is optimized,combined with alumina and PMMA as the composite insulating layer,the best device standoff current of 3.2×10^-9,current switch ratio reached 2.0×10⁴,carrier mobility of up to 2.55cm²/V·s,minimum threshold voltage of 4.5V,the threshold swing 4.4V/dec.It was found that the anodic oxidation insulation layer had an obvious effect on reducing the leakage current of the device.The off-state current decreased by two orders of magnitude and the current switch ratio increased by 12.5 times.The carrier mobility increased by 2.5 times,and the threshold voltage and the sub-threshold amplitude both decreased.