The Research Of ZrO₂-doped Al-Zn-Sn-O Films And TFT Devices Prepared By Co-sputtering

Metal oxide semiconductor-based thin film transistors have the advantages of high mobility,good uniformity,and low process temperature,so they have broad application prospects in the field of flat panel displays.The indium element required by IGZO and other representative metal oxide semiconductors is expensive and toxic.Therefore,indium-free metal oxide semiconductors have attracted the attention of the academic and industrial circles.In this paper,zirconium-doped aluminum-zinc-tin oxide(Zr-AZTO)semiconductor films and devices have been prepared,and the effects of various process parameters on their performance have been studied.First,this study used a ZrO₂ target and an AZTO target with an atomic ratio of Zn:Al:Sn:O=4:0.5:7:18.75,and used the co-sputtering method to prepare a Zr-AZTO thin film.By adjusting the thickness of deposited film,sputtering power,sputtering oxygen content,annealing temperature and other parameters,the effects on the physical and chemical properties,optical properties,oxygen vacancies,Hall mobility,carrier concentration and localized state of the film were studied.The roughness of the film increased with the increase of thickness,and the Hall mobility and bulk carrier concentration increased with the increase of annealing temperature.After optimization,the best process conditions:film thickness is 10 nm?20 nm,ZrO₂ target power is 15 W,AZTO target power is 100 W,annealing temperature is 450?and oxygen content is 5%;film characteristics:transmittance is 82%(@600 nm),hall mobility is4.07 cm²·V^-1·s^-1,and the carrier concentration is 1.96×10¹⁸cm^-3.Secondly,this article uses Zr-AZTO semiconductor thin film as the active layer to successfully fabricate thin film transistor devices.As the thickness increased,the mobility and switching ratio of the device first increased and then decreased.As the annealing temperature increased,the mobility of the device increased,and the stability of the forward bias voltage of the device increased.After optimization,when the process conditions were set as:Zr-AZTO active layer thickness is 10 nm,ZrO₂ target power is 15 W,AZTO target power is 100 W,annealing temperature is 450?and oxygen content is 5%,the?_sat of the device was 18.49cm²·V^-1·s^-1,V_on was-3.25 V,V_th was 1.95 V,I_on/off was 1.36?10⁷,and subthreshold swing was0.21 V/decade.After applying a forward voltage of 20 V for 3600 s,the turn-on voltage of device drifted forward by 2.76 V;after applying a reverse voltage of 20 V for 3600 s,the turn-on voltage of device drifted backward by 5.12 V.