Formation of h BN monolayers through nitridation of epitaxial silicene on diboride thin films

Abstract

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.