Fast All-Transparent Integrated Circuits Based on Indium Gallium Zinc Oxide Thin-Film Transistors

We describe the fabrication and characterization of visible transparent small-scale indium gallium zinc oxide (IGZO) integrated circuits. The IGZO channel and indium tin oxide (ITO) contacts and interconnects were pulsed laser deposited at room temperature. Low-temperature (200 ^??C ) atomic-layer-deposited Al₂O₃ was used as the gate dielectric in bottom-gated thin-film transistors with field-effect mobility near 15 cm²/V??s. Logic inverters and ring oscillators were fabricated and characterized, with operations at frequencies as high as 2.1 MHz, corresponding to a propagation delay of less than 48 ns/stage with a supply voltage of 25 V. To the best of our knowledge, these are the fastest all-transparent oxide semiconductor circuits reported to date.