Performance Optimization And Process Exploration Of IGZO-TFT Devices Prepared By Solution Processing

Amorphous IGZO-TFT has attracted a wide range of research and exploration at home and abroad due to its high carrier mobility,good optical transparency and excellent uniformity.It is supposed that IGZO-TFT will replace the traditional amorphous silicon TFT,for the next generation of flat panel display technology mainstream.IGZO-TFT currently fabricated by expensive vacuum process,such as magnetron sputtering,pulsed laser deposition,atomic layer deposition and so on.Recently,due to the advantages of low cost and large area preparation,solution-processed IGZO-TFT has become a hotspot.In this thesis,we carried out a detailed study on solution-processed IGZO-TFT.At first,we prepared by the solution of Al₂O₃ as the dielectric layer,the initial realization of the whole solution-processed IGZO-TFT preparation.Compared with SiO2,Al₂O₃ has a high dielectric constant? 9.5?,which can reduce the TFT device operating voltage.We used the solution-processed Al₂O₃ as insulating layer and applied it to the IGZO-TFT.The IGZO active layer ratio In : Ga : Zn = 0.42 : 0.25 : 1,which is studied in our group previously.The device parameters of IGZO-TFT are Vth = 0.93 V,Ion/off = 1.04 × 103,? = 1 cm2v-1s-1,S = 0.51 V/Dec.Secondly,we investigated the effect of different atomic ratios on IGZO-TFT performance.Compared with In2O3,IGZO thin films have smoother surface,and lower density of surface defects.This results in IGZO-TFT with excellent performance.In this part,IGZO-TFT is optimized with In : Ga : Zn = 4.67 : 1 : 1,which lead to the device with performance of Vth = 0.23 V,Ion/off = 7.2 × 105,? = 9.1 cm2v-1s-1,S = 0.22 V/Dec.The devices were subjected to +2 V bias for 720 s,the In2O3-TFT and IGZO-TFT showed a threshold voltage shift of 4.07 V and 0.49 V,respectively.We can conclude that the optimized IGZO-TFT has better bias stability than In2O3-TFT.Thirdly,we investigated the influence of post-annealing temperature on the performance of IGZO-TFT.With the increase of annealing temperature,the main defects such as interstitial oxygen Oi in IGZO active layer are reduced,and the surface defect density at the conductive channel become smaller,which improved the device performance.The performance of the TFT device is improved with the increase of the annealing temperature.The 300?-annealed device showed the best performance,with device Vth = 0.26 V,Ion/off = 2.3 × 105,? = 9.92 cm2v-1s-1,S = 0.3 V/Dec.In addition,we carried out a preliminary exploration of the patterning of the IGZO active layer,thereby reducing the leakage current of the device.