Liquid-Metal-Printed Ultrathin Oxides for Atomically Smooth 2D Material Heterostructures.

Two-dimensional (2D) semiconductors are promising channel materials for continued downscaling of complementary metal-oxide-semiconductor (CMOS) logic circuits. However, their full potential continues to be limited by a lack of scalable high- k dielectrics that can achieve atomically smooth interfaces, small equivalent oxide thicknesses (EOTs), excellent gate control, and low leakage currents. Here, large-area liquid-metal-printed ultrathin Ga 2 O 3 dielectrics for 2D electronics and optoelectronics are reported. The atomically smooth Ga 2 O 3 /WS 2 interfaces enabled by the conformal nature of liquid metal printing are directly visualized. Atomic layer deposition compatibility with high- k Ga 2 O 3 /HfO 2 top-gate dielectric stacks on a chemical-vapor-deposition-grown monolayer WS 2 is demonstrated, achieving EOTs of ∼1 nm and subthreshold swings down to 84.9 mV/dec. Gate leakage currents are well within requirements for ultrascaled low-power logic circuits. These results show that liquid-metal-printed oxides can bridge a crucial gap in dielectric integration of 2D materials for next-generation nanoelectronics.