posted on 2022-12-09, 14:36authored byYi Ding, Wenyu Huang, Yi Chang, Yang Song, Gang Chen
Based on density functional calculations, a novel planar
allotrope
of silicon on Al(111) is rationally designed by using the lowest energy
principle, which is also predicted to be stable above room temperature
to suggest the possibility for its fabrication. The corresponding
free-standing sheet would be buckled though the structural characteristics
still
remain, whose stability has also been evaluated in detail. It has
been found to have strong anisotropic properties to be as hard as
silicene in a specific direction and to be very soft in the perpendicular
direction. Surprisingly, a peculiar negative Poisson’s ratio
showing unusual mechanical properties is also found. The indirect
bandgap of 0.14 eV of the free-standing sheet could be closed by applying
tensile strain. Interestingly, the Dirac cone of the orthogonal lattice
allotrope sheet can be obtained by applying biaxial strain, for which
the velocity of the charge carriers could reach 5.97 × 105 m/s. In addition, the hydrogenated sheet is also quite stable
and may find usage for sunlight absorption, field-effect transistor, etc., which may be decorated with Ti, Fe, or Co adsorptions
to have half-metallic conducting properties for spin filtering.