Transparent double-gate IGZO TFTs for high-performance transparent electronics

Abstract We report the fabrication and characterization of transparent thin-film transistors (TFTs) having a double-gate structure with an indium gallium zinc oxide (IGZO) channel and indium tin oxide (ITO) electrodes. The transparent TFTs were fabricated on quartz substrates, with radio-frequency magnetron sputtering of IGZO channels and ITO electrodes. Al 2 O 3 gate insulators were deposited by atomic layer deposition. The devices exhibited excellent transparency, with > 80% visible light transmittance. By precisely adjusting the O 2 flow during IGZO channel deposition, we achieved excellent electrical characteristics such as a maximum mobility of 13.51 cm 2 V −1 s −1 , high I max / I min ratio of 8.9 × 10 6 , and small subthreshold swing of ∼100 mV dec −1 . A gate-bias-dependent transmission line method study indicated that, during operation, the contact resistance is modulated by the field from the double gate. We also evaluated the reliability of the transparent TFTs through positive bias stress/negative bias stress tests and positive bias illumination stress/negative bias illumination stress tests. The proposed devices hold promise for advancing transparent display technologies.