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/O-2 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 x 10(-5) S, a field-effect mobility of 57.2 cm(2)/V . s, an on/off ratio of 4.19 x 10(7), 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.