Semiconducting Bilayer Borophene with High Carrier Mobility.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Borophene exhibits unique properties like Dirac fermions and superconductivity.
• Bilayer borophene offers improved stability against oxidation compared to monolayer forms.
• The impact of metal substrates on borophene's structural stability is often overlooked.

Purpose of the Study:

• To investigate the structural stability of monolayer borophene polymorphs on different metal substrates.
• To identify novel bilayer borophene structures with semiconducting properties.
• To analyze factors influencing the electronic properties and interlayer bonding in bilayer borophenes.

Main Methods:

• First-principle calculations were employed to identify stable borophene polymorphs.
• Density Functional Theory (DFT) was used to model interactions between borophene and metal substrates (Au(111), Ag(111), Cu(111)).
• Electronic band structures were calculated to determine semiconducting properties and band gaps.

Main Results:

• 31 monolayer borophene polymorphs were found to be stabilized on Au(111), Ag(111), and Cu(111) substrates.
• Two novel semiconducting bilayer borophene polymorphs with band gaps of 0.37 eV and 0.42 eV were identified.
• The highest predicted electron mobility reached 2.01 × 10^4 cm^2V^-1s^-1, attributed to interlayer bonding from delocalized electrons.

Conclusions:

• Metal substrates significantly influence the stability of borophene polymorphs.
• The identified semiconducting bilayer borophenes hold promise for low-power electronic applications.
• Understanding interlayer bonding is crucial for tuning the electronic properties of bilayer borophenes.