Single-Phase Borophene on Ir(111): Formation, Structure, and Decoupling from the Support

Artificial two-dimensional (2D) materials, which host
electronic
or spatial structure and properties not typical for their bulk allotropes,
can be grown epitaxially on atomically flat surfaces; the design and
investigation of these materials are thus at the forefront of current
research. Here we report the formation of borophene, a planar boron
allotrope, on the surface of Ir(111) by exposing it to the flux of
elemental boron and consequent annealing. By means of scanning tunneling
microscopy and density functional theory calculations, we reveal the
complex structure of this borophene, different from all planar boron
allotropes reported earlier. This structure forms as a single phase
on iridium substrate in a wide range of experimental conditions and
may be then decoupled from the substrate via intercalation.
These findings allow for production of large, defect-free borophene
sheets and advance theoretical understanding of polymorphism in borophene.