Chemical vapor deposition of two-dimensional boron sheets by thermal decomposition of diborane

Borophene, a one-atom-thick sheet of boron, is one of very few 2D metals and a candidate for ultrathin interconnects in future chips. Until this work it had been grown only by molecular beam epitaxy, which is slow and hard to scale. We grew it for the first time by chemical vapor deposition, using diborane gas as a pure boron source.

• First CVD growth of atomic-thickness borophene sheets.
• Average thickness 4.2 Å, χ₃ crystal structure, metallic conductivity.
• Evidence for stacked bilayer and trilayer borophene.
• Systematic study of how temperature, deposition rate and pressure control growth.

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