Study Of Tungsten Doping Zinc Tin Oxide Thin Film Transistor Via Solution Process

The requirements for display panels are gradually increasing,with the continuous advancement of technology,which require large areas,high resolution,and high frame rate,thereby placing higher demands on TFT devices,especially active layer materials for TFT devices.In recent years,new amorphous oxide thin film transistors have been widely used due to their good electrical properties,high optical transmittance,large area preparation and good uniformity.Doping is an important and good method for improving the performance of thin films and TFT devices.Choosing suitable doping elements is of great significance for improving the properties of thin films and devices.Conventional fabrication of thin film transistors uses a vacuum process,which is extremely expensive to prepare and complicated to maintain.The solution method does not require a vacuum,the process is simple,the cost is low,and the chemical composition ratio of the solution can be accurately controlled.Therefore,it has aroused the attention of researchers.In this paper,a multi-element tungsten-zinc-tin-oxygen?WZTO?was developed by solution method,and the insulating layer silica was prepared by thermal growth.Different tungsten element doping ratios are selected for doping and WZTO thin films and TFT devices are prepared.Characterization of the properties of the unit oxide binary oxide and the multi-element oxide film.Furthermore,the effects of different concentrations of tungsten doping on the properties of WZTO thin films and devices were further analyzed.On this basis,the bias stability and long-term stability of WZTO TFT devices are studied.At the same time,the influence of annealing temperature on the properties of WZTO thin films and devices was studied by using the control variables.The final study analyzed the effect of tungsten doping ratio on the properties of the film and device and the effect of annealing temperature on the properties of WZTO film and device.The main works in this paper are shown as follows:?1?A triangular structure model was established,and unit oxides,binary oxides and ternary oxide films were prepared by solution method.XRD was used to analyze the crystallization of the film.The surface roughness of the film was analyzed by atomic force microscopy?AFM?.Intuitive display of the performance of unit oxides,binary oxides and ternary oxide films,laying the foundation for further study of WZTO ternary oxide films and devices.?2?On the basis of the analysis of triangular structure,the WZTO film and TFT device with different tungsten?W?element doping concentration were prepared by solution method.The transmittance of WZTO film was higher than 85%.Based on the analysis of AFM and XPS,based on the comparison with ZTO film,it is found that the surface roughness of the film decreases with the increase of tungsten?W?element doping concentration,and the oxygen vacancy concentration in the film decreases from40%to 27%,which greatly improves the stability of the WZTO TFT device,and the threshold voltage forward drift is reduced from 3V to 0.5V.The long-term stability is further enhanced,and the off-state change gradually decreases with the doping of the tungsten?W?element.?3?By controlling the variable method,the influence of annealing temperature on the properties of WZTO film and device was studied under the condition of controlling the doping concentration of tungsten?W?element to 1%.As the annealing temperature increases,the defect state in the film and device gradually decreases.The film is still amorphous at 500°C,the surface roughness of the film increases with the increase of annealing temperature,the device performance improves with the increase of annealing temperature,and the device mobility increases from 1.8 cm²/V·S to 2.4.cm²/V·S.The I_on/I_off is 2.1?10⁷ at 500°C,the threshold voltage is 3.48V,and the subthreshold swing is 0.43 V/dec.It is shown that the annealing temperature plays an important role in improving the properties of the film and device.