Circular Architecture for Excellent Uniformity in Amorphous Indium-Gallium-Zinc-Oxide Thin-Film Transistors

We report high-performance amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors(TFTs), in which both rectangular and circular architectures are utilized. In comparison to the commonly used rectangular design, the circular architecture is capable of significantly improving the device-to-device uniformity without obvious deterioration in transistor performance, and the ratio of standard deviation to mean value (variation coefficient) is only 1.29% for threshold voltage (V-TH),1.12% for maximum width-normalized transconductance(G(m,max)), and 0.93% for linear electron mobility (mu(e)), amongthe uniformity records for a-IGZO TFTs. Furthermore, simulations show a good agreement with experimentaldata and demonstrate that the improvement in device-to-device uniformity of circular architecture originates fromthe elimination of edge conduction paths compared torectangular layout.