In order to improve the electrical performance of the thin film transistors, a kind of high dielectric constant material is used instead of the conventional SiO2 as the gate dielectric. Compared with the SiO2, Ta2O5 has a high-k value with semiconductor process compatibility, which exhibits the potential to overcome the problem of leakage current and thereby become a new generation of gate dielectric materials. Firstly, Ta2O5 thin films were prepared by magnetron sputtering. AZO-TFTs were fabricated with Ta2O5 as gate dielectric. Then, the effects of oxygen to argon ratio on the properties of Ta2O5 thin films and the electrical properties of AZO-TFT were studied. The influence of surface morphology and roughness of Ta2O5 thin films on the performance of thin film transistors was analyzed. Finally, the electrical properties of SiO2 gate dielectric and Ta2O5 gate dielectric thin film transistors were compared. Experimental results indicate that the performance of TFT is the best when the oxygen argon ratio of TFT is 10∶90. Compared with the TFT using SiO2 as the insulating layer, the on-off current radio of TFT with Ta2O5 as the insulating layer increases from 1.02×103 to 2×104. The subthreshold swing decreases from 5 V瘙
簚dec-1 to 1.5 V瘙
簚dec-1. The field effect mobility increases from 1.6 cm2/(V·s) to 12.2 cm2/(V·s). The electrical performance of the TFT has been improved to some extent.