Performance Investigation of Amorphous InGaZnO Flexible Thin-Film Transistors Deposited on PET Substrates

Amorphous indium gallium zinc oxide (a-InGaZnO) flexible thin-film transistors (TFTs) were deposited on polyethylene terephthalate (PET) substrates at low temperature using a triple-targets magnetron radio frequency (RF) cosputter system. During the deposition of InGaZnO films, triple targets of In₂O₃ target, Ga₂O₃ target, and Zn target were simultaneously sputtered. By varying the mixing gas ratios, the Ar/O₂ ratio of 55 sccm/45 sccm was used as the sputtering gases to deposit the InGaZnO channel layer. The bottom-gate-type triple-targets InGaZnO flexible TFTs operated in n-type enhancement mode with a transconductance of 4.95×10^-5 S, a field-effect mobility of 57.2 cm²/V·s, an on/off ratio of 4.19×10⁷, a turn-on voltage of 0 V, a threshold voltage of 2.5 V, and a subthreshold swing of 0.23 V/decade, which were much better than those of the single InGaZnO target flexible TFTs.