Amorphous Indium-Gallium-Zinc-Oxide TFTs Patterned by Self-Aligned Photolithography Overcoming the GHz Threshold

In this letter, we demonstrate amorphous indium-gallium-zinc-oxide (IGZO) thin-film transistors (TFTs) with a maximum transit frequency (f
_T
) of 1.1 GHz and maximum oscillation frequency (f
_max
) of 3.1 GHz, which set a new record for metal-oxide TFTs based on scalable and cost-effective process techniques. A key for the outstanding high-frequency performance of our TFTs is an optimized two-step self-alignment concept, which allows the rigorous minimization of parasitic elements, that typically limit high-frequency operation. We expect that our results will inspire a wide range of high-frequency circuits based on metal-oxide electronics.