Intrinsic Charge Transport in Stanene:Role of Buckling and Electron-Phonon Coupling
作者单位：Department of ChemistryTsinghua University Institute for Materials ResearchTohoku University Genome InstituteShanghai University
会议名称：《第十三届全国量子化学会议》
会议日期：2017年
学科分类：081704[工学-应用化学] 07[理学] 070304[理学-物理化学(含∶化学物理)] 08[工学] 0817[工学-化学工程与技术] 0703[理学-化学]
关 键 词：stanene electron-phonon couplings carrier mobility calculation density functional perturbation theory two-dimensional materials
摘 要：Among two-dimensional materials, group IV elemental sheets such as graphene, silicene,germanene and stanene have been intensively investigated by first principles calculation.[1] We look at the intrinsic carrier mobility for stanene, or the tin-monolayer, using Boltzmann equation coupled with density functional perturbation theory plus Wannier extrapolation approximation to consider electron scattering with all the phonon branches with dispersion contribution.[2] It is found that the conventional deformation potential(DP) approach proposed by Long et al.,[3] which worked well for many layered materials, can well overestimate the carrier mobility in stanene because the buckled structure allows more types of electron-phonon scattering, such as acoustic flexural mode. DP theory assumed that only longitudinal acoustic phonon in long wavelength limit(|q| ～ 0) contributes to the charge relaxation process. In this work, we calculate all phonon modes, such as out-of-plane acoustic mode, transverse acoustic mode, and optical counterparts, in addition to longitudinal acoustic mode, plus dispersion effects and we investigate the intrinsic carrier mobility, in comparison with the DP theory. We find that the intrinsic carrier mobility could be as high as 2～3 × 10 cm V s by DP theory but becomes only 2～3 × 10 cm V s by the full evaluation of electron-phonon coupling. It is found that the intervalley scattering process in acoustic out-of-plane and transverse mode,which DP ignored dominate the carrier relaxation.