Stabilization and metallic to semiconducting transition in 2D boron sheet

Bucked triangular, β₁₂ and χ₃ are the three lattices of atomic-thin boron sheet which have been realized experimental very recently. The three lattices all are metallic and dynamical unstable. By adopting the first-principles method based on the density functional theory, we predict the biaxial strain under which the β₁₂ and χ₃ boron sheets are stabilized. We also demonstrate the effectiveness of hydrogenation on stabilize the buckled triangular boron sheet. Additional, our calculations show that neither uniaxial nor biaxial strain stabilizes the buckled triangular boron sheet, and when the applied biaxial strain is larger than 14%, its anisotropic conductivity no longer exists. Moreover, the electronic band structures of the three boron sheets are controllable by modifying the hydrogen coverage. We find the Dirac cone in the fully hydrogenated buckled triangular boron sheet, and the metal-semiconducting transition in β₁₂ and χ₃ boron sheet caused by 100% and 50% hydrogenation. Our results reveal new electronic properties for the new class of 2D materials, borophene in the applications of electronics.