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 ( ${V}_{\text {TH}}$ ), 1.12% for maximum width-normalized transconductance ( ${G}_{\text {m,max}}$ ), and 0.93% for linear electron mobility ( $\mu _{\text {e}}$ ), among the uniformity records for a-IGZO TFTs. Furthermore, simulations show a good agreement with experimental data and demonstrate that the improvement in device-to-device uniformity of circular architecture originates from the elimination of edge conduction paths compared to rectangular layout.