Graphene nanostructures

STM Image of a Graphene Ripple

The underlying theme of this research is the study of graphene in the presence of confinement and varied boundary conditions. A necessary step is the preparation of nanostructured graphene. The formation of nanostructures of this 2D material necessarily leads to the existence of edges with significantly modified electronic properties. Edge states and level quantization effects are not the intrinsic and interrelated consequences of the broken symmetry and quantum confinement. As the inherent boundaries of graphene quantum dots, edge structures impose potentials that vary at the nanometer scale, representing a model system to explore relativistic quantum systems in condensed matter experiments under conditions unreachable for truly massless particles. The research in the edge stability and reconstruction will lead to new discoveries in graphene such as chaotic energy level quantization, edge spin-polarization, and Anderson localization induced by edge disorder.

We are well positioned to conduct this research with in situ growth capability, a unique combination of low-temperature atomic resolution STM and AFM, accompanied by DFT calculations.

Representative publications:

  1. Direct experimental determination of onset of electron-electron interactions in gap opening of zigzag graphene nanoribbons”, Y. Y. Li, M. X. Chen, M. Weinert, and L. Li, Nat. Commun. 5, 4311(2014).
  2. Direct experimental evidence for the reversal of carrier type upon hydrogen intercalation in epitaxial graphene/SiC(0001)”, S. Rajput, Y. Y. Li, and L. Li, Appl. Phys. Lett. 104, 041908(2014).
  3. Spatial fluctuations in barrier height at the graphene-silicon carbide Schottky contact”, S. Rajput, M. Chen, Y. Liu, Y. Y. Li, M. Weinert, and L. Li, Nat. Commun. 4, 2752 (2013).
  4. Epitaxial graphene on SiC(0001): More Than Just Honeycombs”, Y. Qi, R. H. Rhim, G. F. Sun, M. Weinert, and L. Li, Phys. Rev. Lett. 105, 085502 (2010).
  5. Atomic-scale imaging and manipulation of ridges on epitaxial graphene on 6H-SiC(0001)”, G. F. Sun, J. F. Jia, Q. K. Xue, and L. Li, Nanotechnology 20, 355701 (2009).