Amorphous Indium-Gallium-Zinc-Oxide Thin-Film Transistor for High Performance Display and Detector
Alex Kuo and Jerzy Kanicki
Amorphous indium gallium zinc oxide thin-film transistor (a-IGZO TFT) has generated many interests among the semiconductor-based flat-panel display and photo-detector. Due to its high amorphous phase field-effect mobility (12.8 cm2V-1s-1), large on-off current ratio (>107), and fabrication simplicity, a-IGZO TFT can be used as an alternative to a-Si:H TFT or even poly-Si TFT backplane technology. It is capable of being used as the driving electronic for a high-resolution display and detector as it can conduct a high drain current level without requirement for a large W/L ratio. The low TFT off current allows the possibility of realizing display with a large gray scale and detector with a large dynamic range. Moreover, the a-IGZO TFT has a low threshold voltage (< 0.21V), which means that its operational power consumption is low. Lastly, the steep subthreshold swing (175 mV/dec) allows the fast switching of the transistor between the on- and off- regimes of operation. Below channel length of 7 µm, the TFT begins to show short-channel effect, where the threshold voltage decreases with channel length, and the contribution of contact resistance begins to affect its conduction. This study was done in collaboration with Canon Inc. (Japan) and was partially supported by DARPA/MTO HARDI program.
