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D. Steiner, F. Mittendorfer, E. Bertel:
"Quasiliquid Layer Promotes Hexagonal Boron Nitride (h-BN) Single-Domain Growth: h-BN on Pt(110)";
ACS Nano, 13 (2019), 7083 - 7090.

Hexagonal boron nitride (h-BN) monolayers were grown
on Pt(110) using borazine as a precursor molecule. The resulting surface
structure was studied by scanning tunneling microscopy, low-energy
electron diffraction, and density functional theory calculations. Borazine
fragments reduce the roughening temperature of pristine Pt(110) (Tr =
1090 K); consequently, growth below T = 1100 K results in a serrated h-
BN/Pt(110) surface with small terraces, defects, and domain boundaries.
Surprisingly, h-BN deposition at T > 1100 K yields large terraces covered
by a carpet-like single-domain h-BN monolayer. Despite the incom-
mensurability and different symmetry, the epitaxial growth is almost
perfect. The key to this counterintuitive behavior is the "soft" Pt(110)
surface responding to the h-BN overlayer in two ways: First, the (1 × 2)-
missing-row (m.r.) reconstruction is converted into a (1 × n)-m.r.
reconstruction with a regular alternation of n = 5 and 6, yielding a
superperiodicity of the Moiré pattern. Second, the remaining rows experience significant relaxations. Some Pt surface atoms are mobile underneath the h-BN monolayer, even at room temperature. Under growth conditions, the top metal layer is disordered and highly mobile, rendering the h-BN growth comparable to that on liquid gold. Such a mechanism may be of general relevance for the epitaxial growth of 2D materials. Because epitaxial deposition of Pt(110) on various substrates has been demonstrated, the present system appears scalable, and its regular 1D grooves render it a promising template for nanowire arrays.

hexagonal boron nitride, Pt(110), 2D materials, epitaxy, chemical vapor deposition, scanning tunneling microscopy, density functional theory