Epitaxial Growth of Two-Dimensional Insulator Monolayer Honeycomb BeO

The emergence of two-dimensional (2D) materials launched a fascinating frontier flatland electronics. Most crystalline atomic layer are based on layered van der Waals with weak interlayer bonding, which naturally leads to thermodynamically stable monolayers. We report the synthesis 2D insulator composed single sheet honeycomb structure BeO (h-BeO), although its bulk counterpart has wurtzite structure. h-BeO is grown by molecular beam epitaxy (MBE) Ag(111) thin films that also epitaxially Si(111) wafers. Using scanning tunneling microscopy and spectroscopy (STM/S), lattice constant determined be 2.65 Å an insulating band gap 6 eV. Our low-energy electron diffraction measurements indicate forms continuous good crystallinity at millimeter scale. Moiré pattern analysis shows maintains long-range phase coherence in registry even across Ag steps. find interaction between substrate using STS complementary density functional theory calculations. not only demonstrate feasibility growing monolayers MBE, but illustrate large-scale growth, interactions, make attractive candidate for future technological applications. More significantly, ability create single-crystalline without intriguing approach tailoring electronic materials.