硅烷的GW准粒子能带修正和BSE光吸收谱的计算

Quasi-Particle Band Structure and Enhanced Excitonic Effect of Silicane by Using GW and BSE Calculation

利用基于GW近似和Bethe-Salpeter方程(BSE)的第一性原理多体微扰方法,计算了二维间接带隙半导体材料椅形硅烷(chairlike silicane)能带的准粒子修正以及光吸收谱。椅形硅烷的电子间强的相互作用显著影响着电子结构,其间接带隙从2.08 eV修正到3.53 eV,直接带隙从2.44 eV修正到3.85 eV。通过比较GW和BSE的光学吸收谱,发现椅形硅烷的束缚激子的束缚能可以达到0.40 eV,远大于硅体材料的15 meV激子束缚能。椅形硅烷的显著激子效应对于硅烯纳米材料的光电子器件应用有重要意义。

The authors present first-principles calculations of the quasiparticle correction and the optical absorption of chairlike silicane fully hydrogenated silicene by using GW method and Bethe-Salpeter equation（BSE）.Electron-electron interaction significantly affects the band structure of chairlike silicane.The indirect band gap of chairlike silicane increases from 2.08 to 3.53 eV and the direct quasiparticle band gap increases from 2.44 to 3.85 eV upon inclusion of the quasiparticle correction.Electron-hole interaction significantly affects the optical absorption of chairlike silicane.The binding energy of the binding exciton is about 0.40 eV,much larger than the value of 15 meV in the bulk Si.The enhanced excitonic effect is expected to be of importance in optoelectronic applications of silicene-based nanostructures.