Comprehensive Study on the Transport Mechanism of Amorphous Indium-Gallium-Zinc Oxide Transistors

High-performance thin-film transistors TFTs, in which the channel material consisted of amorphous indium-gallium-zinc oxide a-IGZO with a bottom gate architecture, were fabricated for array applications. It was found that the dependence of the field-effect mobility on the channel length was greatly affected by the value of the contact resistance RC. A high contact resistance RCW 200 cm resulted in a significant drop 22.3% in the normalized field-effect mobility for the short channel device 10 m, while contact-limited behavior was hardly seen for the device with a low contact resistance RCW 23 cm. The difference in the channel length dependence of the field-effect mobility was comprehensively investigated based on the conduction mechanism. The fabricated n-channel a-IGZO TFTs with W/L =1 0/10 m exhibited a field-effect mobility of 12.6 cm 2 /V s, threshold voltage of 4.7 V, on/off ratio of 10 8 , and subthreshold gate swing of 0.56 V/decade.