Department of Physics and Astronomy, University of California , Riverside, California 92521, United States.
Department of Physics and Astronomy, Ohio University , Athens, Ohio 45701-2979, United States.
Nano Lett. 2018 Jan 10;18(1):64-69. doi: 10.1021/acs.nanolett.7b03167. Epub 2017 Dec 12.
Confinement of electrons in graphene to make devices has proven to be a challenging task. Electrostatic methods fail because of Klein tunneling, while etching into nanoribbons requires extreme control of edge terminations, and bottom-up approaches are limited in size to a few nanometers. Fortunately, its mechanical flexibility raises the possibility of using strain to alter graphene's properties and create novel straintronic devices. Here, we report transport studies of nanowires created by linearly-shaped strained regions resulting from individual folds formed by layer transfer onto hexagonal boron nitride. Conductance measurements across the folds reveal Coulomb blockade signatures, indicating confined charges within these structures, which act as quantum dots. Along folds, we observe sharp features in traverse resistivity measurements, attributed to an amplification of the dot conductance modulations by a resistance bridge incorporating the device. Our data indicates ballistic transport up to ∼1 μm along the folds. Calculations using the Dirac model including strain are consistent with measured bound state energies and predict the existence of valley-polarized currents. Our results show that graphene folds can act as straintronic quantum wires.
将电子限制在石墨烯中以制造器件已被证明是一项具有挑战性的任务。由于克莱因隧穿，静电方法失败，而刻蚀成纳米带则需要对边缘终止进行极端控制，自下而上的方法在尺寸上受到限制，只能达到几个纳米。幸运的是，其机械灵活性提高了利用应变来改变石墨烯性质并创建新型应变电子器件的可能性。在这里，我们报告了通过线性应变区域创建纳米线的传输研究，该应变区域是通过将石墨烯转移到六方氮化硼上形成的单个折叠产生的。在折叠处的跨导测量中，我们观察到了库仑阻塞特征，表明这些结构内部存在受限电荷，它们充当量子点。在折叠处，我们观察到横电阻测量中的尖锐特征，这归因于通过包括器件的电阻桥对点电导调制的放大。我们的数据表明，在折叠处沿约 1μm 的距离进行弹道传输。包括应变的狄拉克模型的计算与测量的束缚态能量一致，并预测了谷极化电流的存在。我们的结果表明，石墨烯折叠可以充当应变电子量子线。
