Effect of Ta addition of Co-sputtered amorphous tantalum indium zinc oxide thin film transistors with bias stability

In this work, we have fabricated thin film transistors (TFTs) using amorphous tantalum indium zinc oxide (a-TaInZnO) channels by the co-sputtering process. The effects of incorporating tantalum on the InZnO material were investigated using Hall-effect measurement results, and electrical characteristics. We also found that the carrier densities of thin films and the transistor on-off currents were greatly influenced by the composition of tantalum addition. Ta ions have strong affinity to oxygen and so suppress the formation of free electron carriers in thin films; they play an important role in enhancing the electrical characteristic due to their high oxygen bonding ability. The electrical characteristics of the optimized TFTs shows a field effect mobility of 3.67 cm2 V-1 s-1 , a threshold voltage of 1.28 V, an on/off ratio of 1-1 × 108 , and a subthreshold swing of 480 mV/dec. Under gate bias stress conditions, the TaInZnO TFTs showed lower shift in threshold voltage shifts.