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

Integrating high-kappa 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 x 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 10(11)-10(12) cm(-2) eV-1. The synthesized HfO x displays excellent dielectric properties with an EOT of similar to 1.5 nm, i.e., a high kappa of similar to 16, an ultralow leakage current of 10(-6) A/cm(2), 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-kappa dielectrics into vdW sandwich heterostructures holds immense potential for developing low-power consumption 2D electronics while meeting comprehensive dielectric requirements.