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2D materials

Several atomic-layer-thick materials, often referred to as "two-dimensional" (2D) materials, have substantially changed the landscape of nanotechnology because of their extraordinary mechanical and electrical properties. For example, graphene, which exists as a single layer of carbon atoms, possesses a tensile strength 300 times larger than that of commercial steel and transports electric charges over an order of a magnitude faster than silicon.

Our 2D material research[1-3] combines analytical scanning transmission electron microscopy (STEM) and theoretical modeling of electron-material interactions to elucidate unambiguously the atomic, chemical, and electronic structure of novel 2D materials. This research aims to improve the understanding of 2D materials’ enhanced properties as well as aid in their synthesis and device application.

 


Figure: Atomic resolution TEM images of 2D materials. (a) Top panel: SnS TEM image with ball-and-stick overlay. Bottom Panel: SnS2 with overlay. (b) Black phosphorus imaged in the two different crystallographic directions: (top) [100] (bottom) [001]. (c) MoS2 imaged at various thicknesses and compared to simulated images.

Recommended Reading

  1. "Surface-State-Dominated Spin-Charge Current Conversion in Topological-Insulator–Ferromagnetic-Insulator Heterostructures"
    H. Wang, J. Kally, J. S. Lee, T. Liu, H. Chang, D. Reifsnyder Hickey, K. A. Mkhoyan, M. Wu, A. Richardella, and N. Samarth
    - Phys. Rev. Lett. 117, 076601 (2016)

  2. "Giant Spin Pumping and Inverse Spin Hall Effect in the Presence of Surface and Bulk Spin−Orbit Coupling of Topological Insulator Bi2Se3"
    M. Jamali, J. S. Lee, J. S. Jeong, F. Mahfouzi, Y. Lv, Z. Zhao, B. K. Nikolić, K. A. Mkhoyan, N. Samarth, J. P. Wang
    - Nano Lett. 15, 7126 (2015)

  3. "Atomic and electronic structure of exfoliated black phosphorus"
    R. J. Wu, M. Topsakal, T. Low, M. C. Robbins, N. Haratipour, J. S. Jeong, R. M. Wenzcovitch, S. J. Koester, K. A. Mkhoyan
    - J. Vac. Sci. Technol. A 33, 060604 (2015).   [Ed. Pick]  Highlighted on JVSTA Cover.

  4. "Wafer Scale Synthesis and High Resolution Structural Characterization of Atomically Thin MoS2 Layers"
    A. S. George, Z. Matlu, R. Ionescu, R. J. Wu, J. S. Jeong, H. H. Bay, Y. Chai, K. A. Mkhoyan, M. Ozkan, C. S. Ozkan
    - Adv. Funct. Mater. 24, 7461 (2014).

  5. "Determining the thickness of atomically thin MoS2 and WS2 in the TEM"
    R. J. Wu, M. L. Odlyzko, K. A. Mkhoyan
    - Ultramicroscopy 147, 8 (2014).

  6. "Atomic and Electronic Structure of Graphene-Oxide"
    K.A. Mkhoyan, A.W. Contryman, J. Silcox, D.A. Stewart, G. Eda, C. Mattevi, S. Miller, M. Chhowalla
    - Nano Lett. 9, 1058 (2009).


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