Preparation And Research Of Al-Zn-Sn-O Thin Film Transistors

In recent years,the continuous progress of science and technology,lead to the development of intelligent wearable electronic devices industry to flourish,electronic display devices have been increasing attention.Thin film transistor as the core component of electronic display screen,has a wide range of application in bending,wearable and portable display devices.Because of its better stability and higher mobility,the oxide thin film transistor is easy to be prepared at room temperature,so it is of great significance in the field of screen display research.Among the oxide semiconductor thin film transistors,indium gallium zinc oxide thin film transistors have been widely studied.Indium and gallium are rare and toxic elements in nature,which is not conducive to large-scale fabrication and commercial production.It is one of the most important research in the world to find a new material of thin film transistor.Research shows that the mobility of amorphous oxide films obtains high rate of metal ions,its outer shell electron distribution in the film to meet the(n-1)d10ns0(n=4,n is the main quantum number).At the same time,in order to obtain stable device performance,it is necessary to have a higher binding energy of metal ions to inhibit the formation of oxygen vacancies.In view of the above two points,In the AZTO thin film,Sn also satisfies the(n-1)d10ns0(n?4)electron structure and serves to provide carrier concentration in the film,while the binding energy of Al3+ and O2-binding energy than Ga3+ and O2-high,and can also achieve the role of regulation of carrier concentration,so the theoretical analysis can be achieved on the replacement and fabrication of high-performance AZTO oxide film to replace the IGZO film.The large amount of aluminum and tin in nature and no harm to the human body,through the Sn element instead of In elements,Al elements instead of Ga elements,the fabrication of thin film transistor with excellent performance,in the future of wearable and portable display devices widely used has important significance.In this paper,metal Al target,ZnO and SnO2 ceramic target were used as the material for the fabrication of the active layer AZTO,and a novel indium oxide-free AZTO film was fabricated by magnetron co-sputtering.The properties of the thin film transistor were studied.The results show that the effects of fixed growth pressure,growth temperature and different oxygen partial pressure on AZTO films are as follows: The results show that the AZTO films fabrication under different growth conditions are different oxygen partial pressure on the regulation of Al elements has a significant effect,when the oxygen partial pressure in 5%,in the film Al,Sn,Zn atomic ratio is 2:1:1,the Hall mobility of the film is 3.507 cm2V-1s-1,current carrying the concentration is 2.950E+18.Based on this,the influence of different growth temperature and growth pressure on AZTO thin film was studied under the condition of 5% oxygen partial pressure.The results show that when the temperature is 80 ?,the Hall mobility of the film is 2.146+01cm2V-1s-1,the carrier concentration is 4.323E+17,and the film has good performance.When the growth pressure is 8 mTorr,the Hall mobility of the film is 3.207 cm2V-1s-1 and the carrier concentration is 2.950E+18.Finally,we use the lift-off process to fabrication of anti-overlapping structure AZTO thin film transistor.The oxygen partial pressure of 5%,the growth of the environmental pressure of 8 mTorr and the substrate temperature of 80?,the active layer sputtering metal target Al,ZnO and SnO2 ceramic target preparation of thin film transistor by magnetron co-sputtering,were fabricated AZTO thin film transistor has a thickness of 20 nm,50 nm,80 nm,120 nm,of which the electrical performance test analysis.Results: influence of active layer thickness on the device performance,when the active layer thickness is too thin,the carrier number is too small,the migration rate is too low;and when the active layer thickness is too thick,on the one hand,will increase the carrier injection resistance,on the other hand over thickness will cause the excessive number of carrier scattering,the results.Make the migration rate decreased.It was found that when the active layer of the thin film transistor was 50 nm,the thin film transistor the mobility is 2.17 cm2v-1s-1,the threshold voltage is 14 V,the switching current ratio is 1.84 × 104,and the overall performance of the device is relatively good.