Oh Sehoon, Crommie Michael F, Cohen Marvin L
Department of Physics , University of California at Berkeley , Berkeley , California 94720 , United States.
Materials Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States.
ACS Nano. 2019 Feb 26;13(2):1713-1718. doi: 10.1021/acsnano.8b07781. Epub 2019 Feb 4.
We investigate the atomic and electronic structures of cyclooctatetraene (COT) molecules on graphene and analyze their dependence on external gate voltage using first-principles calculations. The external gate voltage is simulated by adding or removing electrons using density functional theory calculations. This allows us to investigate how changes in carrier density modify the molecular shape, orientation, adsorption site, diffusion barrier, and diffusion path. For increased hole doping, COT molecules gradually change their shape to a more flattened conformation and the distance between the molecules and graphene increases while the diffusion barrier drastically decreases. For increased electron doping, an abrupt transition to a planar conformation at a carrier density of -8 × 10 e/cm is observed. These calculations imply that the shape and mobility of adsorbed COT molecules can be controlled by externally gating graphene devices.
我们利用第一性原理计算研究了石墨烯上环辛四烯（COT）分子的原子和电子结构，并分析了它们对外部栅极电压的依赖性。通过使用密度泛函理论计算添加或移除电子来模拟外部栅极电压。这使我们能够研究载流子密度的变化如何改变分子形状、取向、吸附位点、扩散势垒和扩散路径。对于增加的空穴掺杂，COT分子逐渐将其形状变为更扁平的构象，分子与石墨烯之间的距离增加，而扩散势垒急剧降低。对于增加的电子掺杂，在载流子密度为-8×10 e/cm时观察到向平面构象的突然转变。这些计算表明，吸附的COT分子的形状和迁移率可以通过外部控制石墨烯器件的栅极来控制。
