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Abstract
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In the present study, the effects of the configuration buckling on dielectric function of
silicene, germanene and stanene are investigated. The behavior of the optical absorption
spectrum and the refractive index dispersion are studied using the density functional
theory in terms of incident photon energy at different buckling heights. The results show
that for a fixed bond length, increasing the unit cell buckling height, increases the absorption
and the refractive index in silicene and germanene but decreases in stanene. In
addition, the absorption peaks shift toward the longer wavelengths (red shift) in the case
of silicene and germanene by increasing the buckling height. For clear understanding of
the mentioned results, the behavior of the optical absorption spectrum and refractive
index dispersion at different buckling heights are studied within the present work. In the
case of the silicene and germanene reduction of the band gap with increasing the buckling
height could be regarded as the origin of this red shift. Meanwhile unlike the silicene and
germanene, band-structure reshaping in stanene could explain the stanene blue shift as a
result of the buckling height increment.
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