Gunst Tue, Kaasbjerg Kristen, Brandbyge Mads
Department of Micro- and Nanotechnology (DTU Nanotech), Center for Nanostructured Graphene (CNG), Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark.
Phys Rev Lett. 2017 Jan 27;118(4):046601. doi: 10.1103/PhysRevLett.118.046601.
Graphene has an extremely high carrier mobility partly due to its planar mirror symmetry inhibiting scattering by the highly occupied acoustic flexural phonons. Electrostatic gating of a graphene device can break the planar mirror symmetry, yielding a coupling mechanism to the flexural phonons. We examine the effect of the gate-induced one-phonon scattering on the mobility for several gate geometries and dielectric environments using first-principles calculations based on density functional theory and the Boltzmann equation. We demonstrate that this scattering mechanism can be a mobility-limiting factor, and show how the carrier density and temperature scaling of the mobility depends on the electrostatic environment. Our findings may explain the high deformation potential for in-plane acoustic phonons extracted from experiments and, furthermore, suggest a direct relation between device symmetry and resulting mobility.
石墨烯具有极高的载流子迁移率，部分原因是其平面镜面对称性抑制了被高度占据的声学弯曲声子的散射。石墨烯器件的静电门控可以打破平面镜面对称性，产生与弯曲声子的耦合机制。我们使用基于密度泛函理论和玻尔兹曼方程的第一性原理计算，研究了几种栅极几何形状和介电环境下栅极诱导的单声子散射对迁移率的影响。我们证明了这种散射机制可能是迁移率的限制因素，并展示了迁移率的载流子密度和温度标度如何依赖于静电环境。我们的发现可能解释了从实验中提取的面内声学声子的高形变势，此外，还表明了器件对称性与由此产生的迁移率之间的直接关系。
