Formation of hBN monolayers through nitridation of epitaxial silicene on diboride thin films

The formation process of hexagonal boron nitride (hBN) monolayer sheets on single-crystalline ZrB₂(0001) thin films grown on Si(111) wafers has been investigated by electron diffraction, scanning tunneling microscopy, and photoelectron spectroscopy. A two-step reaction was identified, resulting first in the formation of a silicon nitride layer by room temperature exposure of the silicene-terminated ZrB₂ thin film surface to nitrogen radicals and then in the formation of an hBN monolayer replacing the silicon nitride layer through annealing at 900 °C. A large-scale moiré pattern and a clear dispersion of the π-electronic band provide evidence for the formation of an epitaxial hBN monolayer sheet directly on the diboride surface. The unique ability of the ZrB₂(0001) surface, upon which both silicene and hBN monolayers can be formed, opens a way toward the integration of these two very different two-dimensional materials.