High-Speed Dual-Gate a-IGZO TFT-Based Circuits With Top-Gate Offset Structure

Owing to bulk-accumulation, dual-gate (DG) amorphous-indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) with top- and bottom-gates electrically tied together (DG-driving) exhibit 2.53 times higher ON-current and subthreshold voltage swing of ~ 180 mV/decade, which is 50% lower than that of single-gate (SG)-driven a-IGZO TFTs. Here, through simulation and experimental results, we demonstrate that the use of DG-driven back-channel-etched a-IGZO TFTs with a top-gate offset structure enhances the switching speed of a-IGZO TFT-based circuits. In particular, fabricated SG-driven and DG-driven 11-stage ring oscillators exhibited respective oscillating frequencies of 334 and 781 kHz.