Composition Regulation And Structure Design Of Doped Metal Oxide Thin Film Transistor

Active matrix liquid crystal display(active matrix liquid crystal display,The core component of the drive circuit of AMLCD and active matrix organic light-emitting diode（AMOLED）,whose performance directly affects the display effect.The Metal Oxide Thin Film Transistor（MOTFT）has wide application potential in improving the performance and stability of the transistor due to its high mobility,low temperature preparation and large area film formation.At present,the most popular methods of MOTFT preparation include RF magnetron sputtering and atomic layer deposition.Although these methods are mature,they often require the use of traditional vacuum technology,which requires high vacuum,resulting in high preparation costs and complex fabrication processes.With the continuous development of the market,the process of low cost and large area integrated electronic components has become the development trend,while inkjet printing technology has become a strong competitor due to its advantages of low cost,no vacuum requirements,easy control and so on.In this paper,the dual active layer thin film transistor is fabricated by RF magnetron sputtering.Next,MOTFT with different element ratios were prepared by ink-jet printing process.Meanwhile,the relationship between ink-jet printing technology and properties and element components was systematically studied,and the preparation process was continuously optimized.Thin film transistor devices on hard substrates are fabricated without vacuμm.The main research contents include:（1）Two active layer indiμm-free metal oxide thin film transistor（Zn O/AZO-TFT）was prepared by magnetron sputtering at room temperature.The growth sequence of Al-doped zinc oxide（AZO）and zinc oxide（Zn O）double active layers on Si/Si O₂substrate was changed by magnetron sputtering to adjust the field effect properties of TFT.Through experimental analysis,the performance of Zn O/AZO/Si O₂/Si dual-active layer TFT devices is obviously better than that of single AZO or Zn O active layer and inverted AZO/Zn O/Si O₂ dual-active layer TFT devices.The active layer with a higher carrier concentration（AZO in this case）is closer to the dielectric layer,which is more favorable for carrier regulation in TFT devices.In addition,the annealed device has a lower on/off ratio(I_on/I_off),easier to reach the on-on state and higher mobility.At the same time,the performance of the devices annealed in vacuum is obviously better than that in air atmosphere.Ion/Ioff can reach 6.8×105,and the threshold voltage is only2.9V.（2）In GaZnO（IGZO）films and Igzo-TFT devices were prepared by inkjet printing.The effects of different ratios of indium,gallium and zinc on their field effect properties were investigate.Experiments show that with the increase of molar specific gravity In,the carrier mobility of IGZO films increases from 0.004 to 0.072,and the switching ratio of IGZO films increases from 1.41x10⁴ to 2.16x10⁵.In this experiment,the ratio of In:Ga:Zn in the precursor solution with the optimal ratio of IGZO-TFT is 2:1:7.Through the study of the effect of different annealing temperature on the device,it is found that with the increase of annealing temperature,the performance parameters of the device reach the optimal after annealing at 550°C.However,the electrical properties of IGZO-TFT begin to decline when the annealing temperature increases further.（3）Triple oxide IGZO,In Sn Zn O（ITZO）devices and binary oxide In Zn O（IZO）,In Sn O（ITO）devices were fabricated using inkjet printing technology.After experimental analysis,the performance of IGZO-TFT is superior to that of ITZO-TFT.It is concluded that compared to Sn element,the performance of Ga element is more improved than that of TFT,while the performance of IZO-TFT is better than that of ITO-TFT.It is concluded that compared to Sn element,the performance of Zn element is more improved than that of TFT.Secondly,the influence of different heat treatment atmospheres on the surface morphology and device performance of TFT with different active layer materials was studied.Research has shown that the annealing environment can have a significant impact on TFTs with different active layer materials.Among them,annealing in a vacuum environment can optimize the performance of TFT devices.