Controllable Epitaxial\nGrowth of Adlayer-Free Hexagonal\nBoron Nitride Monolayers on Silicon-Incorporated Ni(111) Substrates\nfor Metal–Insulator–Metal Tunneling Devices

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