In₂O₃–ZnO Superlattice Transistors by Atomic Layer Deposition With High Field-Effect Mobility

In this work, we demonstrate high-performance atomic-layer-deposited indium-zinc oxide (IZO) transistors by introducing In2O3-ZnO superlattice, achieving high field-effect mobility (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu _{\text {FE}}\text {)}$ </tex-math></inline-formula>. The electrical properties, such as carrier density and mobility, can be further tuned by the thickness of In2O3 and ZnO layers beyond material composition. The crystallinity of In2O3-ZnO superlattice channel can also be improved by the design of In2O3 and ZnO multilayer. Therefore, an enhanced <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu _{\text {FE}}$ </tex-math></inline-formula> is achieved together with high on/off ratio and steep subthreshold slope (SS). Besides, devices with channel length down to 80 nm are fabricated, with CF4 plasma treatment utilized to suppress carrier density, achieving high on-current, steep SS and enhancement-mode operation. The In2O3–ZnO superlattice enables a new approach to effectively engineer the material properties of oxide semiconductors for further performance enhancement beyond conventional material composition engineering.