Integration of Ultrathin Hafnium Oxide with a Clean van der Waals Interface for Two-Dimensional Sandwich...

Integrating high-κ dielectrics with a small equivalent oxide thickness (EOT) with two-dimensional (2D) semiconductors for low-power consumption van der Waals (vdW) heterostructure electronics remains challenging in meeting both interface quality and dielectric property requirements. Here, we demonstrate the integration of ultrathin amorphous HfO sandwiched within vdW heterostructures by the selective thermal oxidation of HfSe₂ precursors. The self-cleaning process ensures a high-quality interface with a low interface state density of 10¹¹-10¹² cm^-2 eV^-1. The synthesized HfO displays excellent dielectric properties with an EOT of ∼1.5 nm, i.e., a high κ of ∼16, an ultralow leakage current of 10^-6 A/cm², and an impressively high breakdown field of 9.5 MV/cm. This facilitates low-power consumption vdW heterostructure MoS₂ transistors, demonstrating steep switching with a low subthreshold swing of 61 mV/decade. This one-step integration of high-κ dielectrics into vdW sandwich heterostructures holds immense potential for developing low-power consumption 2D electronics while meeting comprehensive dielectric requirements.