Study On The Properties Of Solution-processed Indium-Gallium-Zinc Oxide Thin Films

The amorphous transparent oxide semiconductor?A-TOS?promotes the rapid development of display technology.The amorphous indium gallium oxide zinc oxide?a-IGZO?semiconductor TFT,has gradually received much attention because of their excellent electrical and optical properties,such as the relatively high carrier field effect mobility(?_EE),switching current ratio(I_on/I_off),excellent optical transmittance,qualified homogeneity in large area manufacturing,simple preparation process and low cost,etc.Considering these kinds of advantages,a-IGZO-TFT is widely considered to be the replacement for a-Si,and the important technical node of the new generation display technology.At present,some related original products have come into being both at home and abroad.Although a-IGZO-TFT possesses so many good qualities,it has not be widely employed in the market owing to its instability and unreliability under the bias and light conditions.As is well-known to us,both the liquid crystal display and active matrix light-emitting diode need to work under the condition of light irradiation and voltage bias.Therefore,the bias stability and reliability of a-IGZO-TFT need to be ensured and further improved.Meanwhile,a-IGZO is a kind of amorphous material whose stability and reliability can be seriously affected by the high density interface trap state.In addition,the issue of how to further improve TFT performance from the aspect of the device structure also needs to be deeply explored.In this thesis,the experimental samples are prepared by solution method,aiming to explore the formation of interfacial states and the mechanism of their influence on the current transport,as well as the effects of dual active layers on the electrical properties of TFT from the aspect of device structure.The main findings are summarized as follows.1.The single-layer a-IGZO,a-IZO and double a-IGZO/IZO films samples are prepared under the condition of the annealing temperature at 300?,and their relationships between the variation characteristics and the time of current bias are measured with the Agilent Semiconductor Parameter Analyzer.It is founded that the current variation?I of the a-IGZO/IZO films samples is greater than the single a-IGZO,a-IZO films samples under the same process conditions and test environment.The results further reveal that the carrier transport can be captured by the interfacial carrier trap state while changing the barrier height due to the existence of interfacial carrier traps in double layers structures,2.This study also investigates the effect of annealing temperature on the stability of bilayer films.When the annealing temperature ranges from 220?to 300?,the stability of the double thin films samples can be increased and the current valuation?I is reduced with the change of bias time,which indicates that the density of trapping states at the interface can be decreased with the increase of temperature,thus the carrier trapping rate decreases,that is,the carrier accumulation at the interface decreases,which leads to the reduction of electric field and the barriers in carrier transport can be weakened to some extent.3.The switching current ratio,threshold voltage and mobility of a-IGZO/IZO-TFTN a-IGZO-TFT,a-IZO-TFT device are analysed by using Agilent Semiconductor Parameter Analyzer.At the same time,the output characteristics are tested,and it is found that the dual-active layer device has better performance parameters than the single active layer device,which provides some guiding significance for improving the performance of TFT device.