The Study On Doped GaSnO And InZnO Thin Film Transistors

Thin film transistors(TFTs)are the core components of active matrix displays.Metal oxide TFTs have been extensively studied due to their high mobility,uniformity,and transparency in the visible light.However,faced with the high-performance display requirements of high-resolution,high refresh rate,and etc.,the exploration of new active layer materials and the preparation of metal oxide TFTs with high mobility and good stability have become the research hotspots.To solve this problem,we prepared AGTO TFTs,InZnO:(Li,N)TFTs,InZnO:(Al,N)TFTs,and InZnO:(Li,N)/InZnO:(Al,N)TFTs for the first time.The effects of process conditions on the electrical properties of TFTs were investigated,and the mechanism of different process conditions on the electrical properties of the devices was discussed.At the same time,the stability of the device was studied.The main research work is as follows:(1)AGTO TFTs were successfully prepared by magnetron sputtering.The optical properties of active layer AGTO films were studied by transmission spectroscopy.The structure and morphology of the active layer were studied by XRD and SEM.The effects of active layer thickness and annealing temperature on the electrical properties of AGTO TFTs were studied,and the mechanism is also discussed.Finally,under the optimal preparation conditions,the mobility of the AGTO TFT was 3.9cm2/V s,the threshold voltage is-1.2V,and the on/off ratio is 1.0×106.(2)InZnO:(Li,N)TFTs were successfully prepared by magnetron sputtering.The composition of active layer InZnO:(Li,N)films was studied by EDS and SIMS.The structure and morphology of the active layer were studied by XRD,SEM and AFM.The effect of oxygen flow in sputtering,active layer thickness and annealing temperature on the electrical properties of InZnO:(Li,N)TFTs were studied,and its mechanism was discussed.InZnO:(Li,N)TFT exhibits excellent device performance with a mobility of 53.5cm2/V s.The bias stability of InZnO:(Li,N)TFT and the bias stability of the device under white light irradiation were studied,and the mechanism were discussed.(3)InZnO:(Al,N)TFTs were successfully prepared by magnetron sputtering.The composition of the film was studied by EDS,and the optical properties,structure and morphology of the film were studied by transmission spectroscopy,XRD and AFM.At the same time,the electrical properties of the films were studied by Hall test.The effects of annealing temperature,active layer thickness,oxygen flow rate during sputtering and annealing atmosphere on the electrical properties of the devices were systematically investigated.Finally,the InZnO:(Al,N)TFT mobility can reach 37.6cm2/V s,the threshold voltage is-1.6V,and the on/off ratio is 3.4×108.Finally,the bias stability and environmental stability of InZnO:(Al,N)TFTs were investigated.(4)The double active layer InZnO:(Li,N)/InZnO:(Al,N)TFTs were successfully prepared by magnetron sputtering.The structure and morphology of the films were investigated by XRD and AFM.The effects of the thickness of the upper and lower active layers on the electrical properties of the double active layer TFTs were investigated.Under the optimal preparation conditions,the double active layer device has a mobility of 49.8cm2/V s,a threshold voltage of-2.8V,an on/off ratio of 1.68×109,and a subthreshold swing of 0.61V/decade.In addition,the bias stability of InZnO:(Li,N)/InZnO:(Al,N)TFTs was investigated.