High speed circuit with bulk accumulation mode a-IGZO TFTs

We demonstrate that the use of dual-gate (DG) back-channel-etched amorphous-indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) with channel length of 6 μm and a top-gate offset structure enhances the switching speed of a-IGZO TFT-based circuits. Taking advantage of bulk-accumulation, DG a-IGZO TFTs with top- and bottom-gates physically tied together (DG-driving) achieve high ON-current of ~1 mA at V_GS of 10 V, small sub-threshold voltage swing of 156 mV/dec and near zero-volt turn on voltage (V_ON). The fabricated DG-driven 7-stage ring oscillator (RO) exhibits an oscillating frequency of 3.7 MHz at a supply voltage of 20 V.