Fabrication And Research Of Metal Oxide Thin Film Transistors With Different Element Ratios

As a research hotspot in the semiconductor field,Metal Oxide Thin Film Transistor(MOTFT)has the advantages of high mobility,low temperature preparation,and large area film formation,and researchers are optimistic about its future application in large-size and high-resolution flat panel displays.At present,some display prototype devices based on metal oxide thin film transistor drive with good performance have appeared on the market,but the preparation methods are mostly using traditional vacuum technology,such as magnetron sputtering,vapor deposition,etc.,which require high vacuum in the preparation process,which makes the cost of the equipment manufacturing increase.Currently,the display industry needs to reduce costs and improve efficiency,while at the same time meeting the requirements for large-area integrated electronic components.Among many manufacturing methods,the solution method has become a strong competitor due to its advantages of low cost,no need for vacuum,and easy large-area preparation.Therefore,based on the solution method,this article used spin coating and inkjet printing to prepare metal oxide thin film transistors with different element ratios,and realized the preparation of thin film transistor devices on a rigid substrate in a completely vacuum-free environment.The relationship between its properties and the components of each element and the optimization of the preparation process were systematically studied.The main research content includes:(1)Indium gallium zinc oxide(IGZO)was used as the active layer of thin film transistor devices.In the experiment,In Ga Zn O(IGZO)films and IGZO-TFTs were prepared by solution method,and the influence of different ratios of indium,gallium and zinc on IGZO films and IGZO-TFTs was studied.Experiments show that with the increase in the molar proportion of In,the average electron concentration in the IGZO film increases from 5.41×10¹⁴cm^-3to 2.31×10¹⁶cm^-3,and the average resistivity of the film decreases from 1.77×10⁴?cm to 8.20×10¹?cm.The mobility increased from1.27cm²/Vs to 8.13cm²/Vs.The increase in Ga molar ratio will reduce the average electron concentration in the IGZO film,and the average resistivity of the film will increase,which also reduces the average Hall mobility of the film to a certain extent.In terms of electrical properties,the optimal ratio of indium,gallium,and zinc in the precursor solution prepared in the experiment is 5:2:4.Based on this,the effect of different annealing temperatures on the optimal ratio of IGZO-TFT is studied.The results show initially,as the annealing temperature gradually increased to 550°C,the performance parameters of the device reached the optimum,and the current on-off ratio reached 10⁷.However,with the further increase of the annealing temperature,the current on-off ratio and mobility of the device began to decrease.(2)Indium tin zinc oxide(ITZO)was used as the active layer of thin film transistor devices.In recent years,a-ITZO has begun to receive widespread attention as a possible alternative to a-IGZO.However,there are relatively few researches on the optical properties and electrical properties of ITZO films prepared by solution methods at home and abroad,and most of the preparation processes still use the method of magnetron sputtering deposition.The experiment used zinc acetate dihydrate,stannous chloride dihydrate and indium nitrate hydrate to successfully prepare ITZO precursor solutions with different ratios of indium,tin,and zinc,and used inkjet printing technology to prepare ITZO films and ITZO-TFTs.The effects of different ratios of indium,tin,and zinc on ITZO films and ITZO-TFTs were studied.Experiments show that the ITZO films with different element ratios prepared by the solution method has a transmittance higher than 90%in the visible light region,indicating that the ITZO active layer film has a good optical transmittance.XRD test results show that the prepared ITZO film is an amorphous film.In terms of electrical properties,the optimal ratio of indium,tin,and zinc in the precursor solution prepared in the experiment was 3:1:6,and based on this,the influence of different active layer thicknesses on the optimal ratio of ITZO-TFT was studied.(3)Zinc tin oxide(ZTO)was used as the active layer of thin film transistor devices.Since indium and gallium are both rare elements,this article has carried out research on indium-free metal oxide thin film transistor devices.The experiment successfully prepared ZTO precursor solutions with different element ratios by dissolving zinc acetate dihydrate and stannous chloride dihydrate in ethylene glycol methyl ether,and prepared ZTO-TFTs using inkjet printing technology.The effects of different zinc-tin element ratios on the properties of ZTO films and the ZTO-TFTs prepared were studied.Experiments show that the concentration of Sn doping has little effect on the roughness of the ZTO films,and the prepared ZTO films are relatively dense and flat.In terms of electrical properties,the optimal ratio of zinc to tin in the precursor solution prepared in the experiment is 1:3,and based on this,the influence of different annealing atmospheres on the optimal ratio of ZTO-TFT is studied.