Controllable Epitaxial Growth of Adlayer-Free Hexagonal Boron Nitride Monolayers on Silicon-Incorporated Ni(111) Substrates for Metal–Insulator–Metal Tunneling Devices

Atomically thin hexagonal boron nitride (h-BN) is heralded as the quintessential dielectric for two-dimensional (2D) material-based electronic devices owing to its exceptional properties. The controlled growth of high-uniformity and high-quality 2D h-BN single crystals stands pivotal for diverse applications. Substrate property is one of the crucial factors that influence the quality of epitaxial 2D h-BN films. In this work, we report the study of the molecular beam epitaxial growth of adlayer-free single-crystal h-BN monolayers on Si-incorporated Ni (111) substrates. It was found that Si-incorporated Ni (111) substrates greatly enhanced the uniformity and quality of h-BN monolayer films by eliminating the formation of 3D adlayers during growth. The structural, optical, and electrical properties of these h-BN monolayers were comprehensively characterized. Metal–insulator–metal (MIM) tunneling devices and nanocapacitors were fabricated based on h-BN monolayers to validate their high performance. Our work provides a promising pathway toward the growth of high-quality 2D h-BN and beyond.