School of Science, Chongqing University of Posts and Telecommunications, Chongqing 400065, People's Republic of China.
Hongzhiwei Technology (Shanghai) CO. LTD., 1599 Xinjinqiao Road, Pudong, Shanghai, China.
J Chem Phys. 2023 Feb 28;158(8):084702. doi: 10.1063/5.0134654.
Out-of-plane deformation in graphene is unavoidable during both synthesis and transfer procedures due to its special flexibility, which distorts the lattice and eventually imposes crucial effects on the physical features of graphene. Nowadays, however, little is known about this phenomenon, especially for zero-dimensional bulges formed in graphene. In this work, employing first-principles-based theoretical calculations, we systematically studied the bulge effect on the geometric, electronic, and transport properties of graphene. We demonstrate that the bulge formation can introduce mechanical strains (lower than 2%) to the graphene's lattice, which leads to a significant charge redistribution throughout the structure. More interestingly, a visible energy band splitting was observed with the occurrence of zero-dimensional bulges in graphene, which can be attributed to the interlayer coupling that stems from the bulged structure. In addition, it finds that the formed bulges in graphene increase the electron states near the Fermi level, which may account for the enhanced carrier concentration. However, the lowered carrier mobility and growing phonon scattering caused by the formed bulges diminish the transport of both electrons and heat in graphene. Finally, we indicate that bulges arising in graphene increase the possibility of intrinsic defect formation. Our work will evoke attention to the out-of-plane deformation in 2D materials and provide new light to tune their physical properties in the future.
由于其特殊的柔韧性，石墨烯在合成和转移过程中不可避免会发生面外变形，这会扭曲晶格，最终对石墨烯的物理特性产生至关重要的影响。然而，目前人们对此现象知之甚少，特别是对于石墨烯中形成的零维凸起。在这项工作中，我们采用基于第一性原理的理论计算，系统地研究了凸起对石墨烯的几何、电子和输运性质的影响。我们证明，凸起的形成会在石墨烯的晶格中引入机械应变（低于 2%），这会导致整个结构中的电荷重新分布。更有趣的是，我们观察到在石墨烯中形成零维凸起会导致能带分裂，这可以归因于凸起结构引起的层间耦合。此外，我们发现石墨烯中形成的凸起增加了费米能级附近的电子态，这可能是载流子浓度增强的原因。然而，形成的凸起降低了载流子迁移率并增加了声子散射，从而降低了石墨烯中电子和热的输运。最后，我们指出石墨烯中的凸起增加了本征缺陷形成的可能性。我们的工作将引起人们对面外变形在二维材料中的关注，并为未来调控其物理性质提供新的思路。
