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 ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\textit{V}_{\text{TH}}$</tex-math> </inline-formula> ), 1.12% for maximum width-normalized transconductance ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\textit{G}_{\text{m,max}}$</tex-math> </inline-formula> ), and 0.93% for linear electron mobility ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu _{\text{e}}$</tex-math> </inline-formula> ), 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.