The Study Of Doped Indium Zinc Oxide Semiconductor Thin Films Transistor By Solution-process

Oxide thin film transistors?TFTs?are expected to replace silicon-based TFTs as next-generation display backplanes due to their high carrier mobility and good electrical uniformity.However,the current commercial oxide TFTs still have the disadvantages of high production cost and poor stability.In this paper,in order to reduce the cost and fabricate high-performance TFT devices with high mobility and good stability,we fabricated doped indium zinc oxide?IZO?based on solution process as a semiconductor layer.We have investigated the performance of indium tin zinc oxide?ITZO?TFTs with back channel etching?BCE?structure fabricated by conventional solution method and combustion synthesis method,and then we have studied stability performance of Ln-doped IZO TFT with solution process.The specific resules are as follows:?1?Achieving the BCE structure is a key technology to further reduce production cost,and the BCE structure enables small and fine devices,which is advantageous for high-resolution display.In this paper,the ITZO film was fabricated by solution process,and we studied the etching characteristics of different In/Zn/Sn ratios in wet etching process and S/D etching process at different annealing temperatures.It is found that when In:Zn:Sn=1:1:2can realize the BCE structure,and successfully fabricated the ITZO thin film transistor with BCE structure.In order to fabricate a high mobility TFT device at a low temperature,an ITZO TFT was successfully fabricated by a combustion synthesis method,and the mobility reached8.12 cm²V^-1s^-1,which was more than 6 times higher than the ITZO TFTs using conventional solution process.Moreover,this TFT has a good current switching ratio of 4.5×10⁷,a lower Turn-on voltage of 1.61 V and a smaller subthreshold swing of 0.21 V dec^-1.Through the study of different channel length performance and PBS stability of ITZO TFT,it is found that the ITZO TFT fabricated by the combustion synthesis method has higher short channel performance and better PBS stability.We also investigated the effects of different passivation materials and different SiO₂ film deposition temperatures on ITZO-Hacac TFT devices.It was found that when the SiO₂ film was used as the passivation layer,and the deposition temperature was 250°C,the device has excellent electrical properties and the highest mobility.?2?The stability of the oxide TFT is particularly important for the practical operation of the TFT.In order to obtain a TFT device with good stability we have fabricated a Ln-IZO thin film transistor by solution process.We have investigated the effects of different doping concentrations on the device,it was found that the device mobility decreased with increasing doping concentration.We also investigated the effects of electronegativity and atomic radius of Ln elements on the device,the study showns that the mobility of Ln-IZO TFT is not only related to the electronegativity of Ln element,but also related to the atomic radius.It is found that the lower the electronegativity of Ln-based elements,the lower the mobility of Ln-IZO TFT devices;the smaller the atomic radius of Ln-based elements,the higher the mobility of Ln-IZO TFT devices.Finally,we also compared the stability of IZO TFT and Yb-IZO TFT,the results show that the doping of Yb can effectively improve the bias stability,thermal stability and light stability of the device.