Electronic and optical properties of silicene under uni-axial and bi-axial mechanical strains: A first principle study

• A direct band-gap of 389 meV is found for 6% of uni-axial compression.
• An indirect band-gap of 379 meV is found for 6% of bi-axial compression.
• The π plasmon in silicene disappeared with tensile and asymmetric strains.
• The π+σ plasmons are red-shifted for tensile strains.
• The π+σ plasmons are blue-shifted for compressive strains.

The uni-axial and bi-axial mechanical strain mediated electronic band structures and dielectric properties of silicene have been investigated. It is found that on applying uni- and bi-axial strains, the band gap opens for smaller strain in silicene. However, on further increase of strain beyond 8% silicene changed into metal. The ultimate tensile strength estimated is 3.4 GPa. Imaginary part of dielectric function shows that the inter-band transitions are red-shifted for uni- and bi-axial tensile strains and are blue shifted for uni- and bi-axial compressive strains. Electron energy loss (EEL) function shows that the π+σ plasmon energies are red-shifted for uni- and bi-axial strains and blue-shifted for compressive strains. The π plasmons disappears for tensile and asymmetric strains. Bi-axial asymmetric strain is found to have no influence on inter-band transitions and π+σ plasmon energies.

Dielectric response of uni-axial and bi-axial mechanically strained silicene with different types of strains at different magnitudes (e=0, 0.04, 0.08 and 0.12) is shown in figure.Figure optionsDownload as PowerPoint slide