Fabrication And Properties Of IZO Thin Film Transistor Based On Inkjet Printing Technology

Oxygen thin film transistors have attracted considerable attention in the field of flexible display due to their high mobility,high light transmittance and flexibility.In recent years,with the application of inkjet printing technology in the field of electronic devices,it has many advantages such as low energy consumption,low pollution,low cost,preparation of precision patterns and large-area continuous printing.In this paper,patterned thin film transistors(including active layer and source-drain electrode layer of thin film transistors)were fabricated by inkjet printing technology,and the fabrication process was optimized.Finally,high quality indium-doped zinc oxide(IZO)thin film transistors were obtained.The specific work is as follows:(1)Controlling the volatilization rate of organic solvents to reduce the influence of coffee ring effect during the curing and shaping process of active layer films;separating the thermal decomposition steps of solutes and organic solvents so that they can react independently,avoiding the destruction of the pattern of films caused by the intense exothermic reaction at the same time.TFT active layer patterned thin films with smooth surface and compact structure were fabricated by multi-step annealing and inkjet printing technology.It is the key factor to fabricate TFT devices with good performance.At the same time,it also provides a good printing condition for the follow-up ink-jet printing source and drain electrode.(2)By changing printing speed,inking quantity,inking frequency and line spacing,square silver electrode patterns with clear shape and regular boundary were successfully prepared,which provided good conditions for the preparation of high precision TFT devices.Then,using the optimized process conditions,the square silver electrode was covered on the active layer pattern prepared by inkjet printing,and the complete TFT device was fabricated.The preparation of source-drain electrodes with different printing accuracy is realized.(3)Introduce the technological process of preparing IZO TFT devices on hard substrates by inkjet printing technology,and fabricate TFT devices with active layer films of different thicknesses.The output characteristic curve and transfer characteristic curve of TFT devices are obtained by means of semiconductor parameter test instrument.The important parameters of TFT devices,such as mobility,threshold voltage,sub-threshold swing and current switching ratio,are calculated.By comparing and analyzing the parameters,when the thickness of active layer is 120 nm,the comprehensive performance of IZO TFT device is the best.Based on the above work optimization,the IZO TFT device with good performance has been successfully fabricated,and its mobility is 0.610 cm~2/Vs,the current-switching ratio is 7.4×10~6 and the threshold voltage is–2V.