Semiconducting Bilayer Borophene with High Carrier Mobility

Borophene has attracted much interest due to its rich configurations and novel properties such as Dirac fermions and superconductivity. The recently emerged bilayer borophene mitigates the oxidation problem when exposed to air, yet most studies ignore the influence of charge transfer induced by metal substrates on structural stability. Here we identified 31 monolayer borophene polymorphs that are stabilized on Au(111), Ag(111), or Cu(111) substrates through first-principle calculations. Interestingly, two novel semiconducting bilayer borophene polymorphs with band gaps of 0.37 and 0.42 eV were screened by integrating these monolayers. The formation of interlayer bonding contributed by the delocalized electrons is responsible for the semiconductivity. The predicted highest electron mobility reaches 2.01 x 10(4) cm(2)V(-1) s(-1), implying the possibility as a semiconductor device with a low power consumption. Moreover, light was also systemically thrown on the factors that may affect the electronic properties of bilayer borophenes and the positional preference of interlayer bonds.

Automated summary

By using first-principle calculations, we identified 31 stable monolayer borophene polymorphs on metal substrates. Two novel semiconducting bilayer borophene structures were screened by integrating these monolayers. Factors affecting the electronic properties and interlayer bond position preference of bilayer borophenes were systematically investigated.