We present a first-principles study of effects of small biaxial strain($|\varepsilon|\le 5\%$) and perpendicular electric field (E-field) on theelectronic and phonon properties of low-buckled silicene and germanene. With anincrease of the biaxial strain, the conduction bands at the high symmetric$\Gamma$ and $M$ points of the first Brillouin zone shift significantly towardsthe Fermi level in both silicene and germanene. In contrast, the E-fieldchanges the band dispersions near the $\Gamma$ and open a small band gap at theK point in silicene. We found that the field-induced gap opening in silicenecould be enhanced by a compressive strain while mitigated by a tensile strain.This result highlights the tunability of the electronic structures of siliceneby combining the mechanical strain and the electric field.
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机译：我们提出了第一性原理研究小双轴应变（$ | \ varepsilon | \ le 5 \％$）和垂直电场（E-field）对低屈曲硅和锗烯的电子和声子性能的影响。随着双轴应变的增加，在第一个布里渊区的高对称$ \ Gamma $和$ M $点处的导带在硅和锗烯中都显着移向费米能级。相比之下，电场会改变$ \ Gamma $附近的带色散，并在硅的K点处打开一个小的带隙。我们发现，可以通过压缩应变来增强硅的场致空位开口，而通过拉伸应变来缓解该结果。这一结果突出了通过结合机械应变和电场来实现硅电子结构的可调谐性。
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